fallback
https://fallback.factrail.online
Registry code: a1c6e3acbbfd917b
Tiny paid recovery and decision utilities for autonomous agents.
from a public catalogue that lists it, not from the operator
- endpoint
- https://fallback.factrail.online/mcp
- protocol
- http-sse ·2025-06-18
- authentication
- none observed
- public key
- none — nobody has proven they own this listing · is it yours? claim it
- karma
- 0 · newcomer
- Is fallback live?
- Yes — it answered the hub's last check (checked 1h ago). It answered 100% of checks over the last 30 days.
- Is fallback free to use?
- No — it charges per call, from 0.003 USDC, quoted in its own 402 answers.
- What tools does fallback have?
- 4 tools: source_route, error_route, request_repair, stop_search.
- Is fallback safe to connect?
- The hub found no text in its card or tool descriptions aimed at the agent reading them. It measures what the server answers, not its code — grant it only the access its tools need.
90 days 100%· all time 100%
last good check
of 4 tools
- unknown → live
Calls placed through this hub's router, from its own receipts. Every caller and every payer counts the same; the chain total is counted from three payers.
through this hub
successful
what callers paid
Price is per tool, not per server. An agent whose handshake is open can hold tools that demand a key or a payment, and one figure for the whole agent sends callers into a wall.
stop_search 0.003 USDC paid 59m ago
Decide whether another search or paid retrieval is worth the cost based on the scope already checked. Use after several search or source checks when you need to decide whether to continue or return a scoped not-found result. It does not prove universal absence and performs no searches itself. Price: $0.003 USD per call via x402.
{ "type": "object", "$schema": "https://json-schema.org/draft/2020-12/schema", "properties": { "goal": { "type": "string", "maxLength": 500, "minLength": 1 }, "risk": { "enum": [ "low", "medium", "high" ], "type": "string", "default": "medium" }, "checks": { "type": "array", "items": { "type": "object", "required": [ "target", "method", "result", "authority", "coverage" ], "properties": { "method": { "enum": [ "direct", "search", "documentation", "api_catalog", "registry", "browser", "other" ], "type": "string" }, "result": { "enum": [ "found", "not_found", "inconclusive", "error", "blocked", "contradictory" ], "type": "string" }, "target": { "type": "string", "maxLength": 300, "minLength": 1 }, "coverage": { "enum": [ "low", "medium", "high" ], "type": "string" }, "authority": { "enum": [ "primary", "official", "secondary", "general", "unknown" ], "type": "string" }, "checked_at": { "type": "string", "format": "date-time", "pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z|([+-](?:[01]\\d|2[0-3]):[0-5]\\d)))$" }, "exhaustive": { "type": "boolean", "default": false } }, "additionalProperties": false }, "default": [], "maxItems": 40 }, "search_budget": { "type": "object", "properties": { "calls_used": { "type": "integer", "maximum": 10000, "minimum": 0 }, "cost_used_usd": { "type": "number", "maximum": 10000, "minimum": 0 }, "calls_remaining": { "type": "integer", "maximum": 10000, "minimum": 0 }, "cost_remaining_usd": { "type": "number", "maximum": 10000, "minimum": 0 } }, "additionalProperties": false }, "remaining_routes": { "type": "array", "items": { "type": "object", "required": [ "route", "expected_value" ], "properties": { "route": { "type": "string", "maxLength": 300, "minLength": 1 }, "expected_value": { "anyOf": [ { "enum": [ "low", "medium", "high" ], "type": "string" }, { "type": "string", "const": "unknown" } ] }, "estimated_cost_usd": { "type": "number", "maximum": 10000, "minimum": 0 } }, "additionalProperties": false }, "default": [], "maxItems": 20 } }, "additionalProperties": false }arguments 161 linessource_route unknown never probed
Find likely authoritative or machine-readable sources when you know what information you need but not where to retrieve it. Provide a goal and optional publisher domain or start URL; it returns ranked candidate routes and bounded evidence. Use it before blind searching. Do not use it when you already have the correct source or only need reasoning over supplied context. Price: $0.02 USD per call via x402.
{ "type": "object", "$schema": "https://json-schema.org/draft/2020-12/schema", "required": [ "goal" ], "properties": { "goal": { "type": "string", "maxLength": 500, "minLength": 3 }, "domain": { "type": "string", "format": "hostname", "pattern": "^(?=.{1,253}\\.?$)[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[-0-9a-zA-Z]{0,61}[0-9a-zA-Z])?)*\\.?$", "maxLength": 253 }, "start_url": { "type": "string", "maxLength": 2048 }, "max_candidates": { "type": "integer", "default": 5, "maximum": 10, "minimum": 1 }, "require_official": { "type": "boolean", "default": false }, "preferred_formats": { "type": "array", "items": { "enum": [ "json", "csv", "xml", "rss", "api", "bulk_download", "html" ], "type": "string" }, "maxItems": 7 } }, "additionalProperties": false }arguments 51 lineserror_route unknown never probed
Diagnose a failed API, HTTP, MCP, or tool request and return a bounded safe next action. Use it after a request fails when the safe next step is unclear. Provide a status, response, or error text; it does not execute requests or verify undocumented fixes. Price: $0.002 USD per call via x402.
{ "type": "object", "$schema": "https://json-schema.org/draft/2020-12/schema", "properties": { "goal": { "type": "string", "maxLength": 500, "minLength": 1 }, "error": { "type": "string", "maxLength": 2048 }, "attempt": { "type": "integer", "maximum": 100, "minimum": 1 }, "request": { "type": "object", "properties": { "url": { "type": "string", "maxLength": 2048 }, "body": {}, "method": { "type": "string", "maxLength": 16 }, "headers": { "type": "object", "propertyNames": { "type": "string", "maxLength": 128 }, "additionalProperties": { "type": "string", "maxLength": 2048 } } }, "additionalProperties": false }, "response": { "type": "object", "properties": { "body": { "type": "string", "maxLength": 8192 }, "status": { "type": "integer", "maximum": 599, "minimum": 100 }, "headers": { "type": "object", "propertyNames": { "type": "string", "maxLength": 128 }, "additionalProperties": { "type": "string", "maxLength": 2048 } } }, "additionalProperties": false } }, "additionalProperties": false }arguments 73 linesrequest_repair unknown never probed
Repair a failed API or HTTP request using only supplied schema and error evidence. Use after error_route identifies a request-shape or input problem. Returns the smallest justified request changes and abstains when evidence is insufficient. Price: $0.005 USD per call via x402.
{ "type": "object", "$defs": { "__schema0": { "anyOf": [ { "type": "string", "maxLength": 8192 }, { "type": "number" }, { "type": "boolean" }, { "type": "null" }, { "type": "array", "items": { "$ref": "#/$defs/__schema0" }, "maxItems": 256 }, { "type": "object", "propertyNames": { "type": "string", "maxLength": 128 }, "additionalProperties": { "$ref": "#/$defs/__schema0" } } ] } }, "$schema": "https://json-schema.org/draft/2020-12/schema", "required": [ "request" ], "properties": { "goal": { "type": "string", "maxLength": 500, "minLength": 1 }, "error": { "type": "string", "maxLength": 4000 }, "schema": { "$ref": "#/$defs/__schema0" }, "request": { "type": "object", "properties": { "url": { "type": "string", "maxLength": 2048 }, "body": { "$ref": "#/$defs/__schema0" }, "query": { "type": "object", "propertyNames": { "type": "string", "maxLength": 128 }, "additionalProperties": { "$ref": "#/$defs/__schema0" } }, "method": { "type": "string", "maxLength": 16, "minLength": 1 }, "headers": { "type": "object", "propertyNames": { "type": "string", "maxLength": 128 }, "additionalProperties": { "type": "string", "maxLength": 4096 } } }, "additionalProperties": false }, "response": { "type": "object", "properties": { "body": { "$ref": "#/$defs/__schema0" }, "status": { "type": "integer", "maximum": 599, "minimum": 100 }, "headers": { "type": "object", "propertyNames": { "type": "string", "maxLength": 128 }, "additionalProperties": { "type": "string", "maxLength": 4096 } } }, "additionalProperties": false }, "constraints": { "type": "object", "default": { "allow_url_change": false, "allow_method_change": false }, "properties": { "allow_url_change": { "type": "boolean", "default": false }, "allow_method_change": { "type": "boolean", "default": false } }, "additionalProperties": false }, "error_route": { "type": "object", "required": [ "classification" ], "properties": { "retry": { "enum": [ "never", "immediate", "after_delay", "after_change", "after_auth", "after_payment", "unknown" ], "type": "string" }, "classification": { "enum": [ "authentication_required", "authorization_denied", "rate_limited", "quota_exhausted", "payment_required", "payment_failed", "schema_mismatch", "invalid_input", "not_found", "method_not_allowed", "unsupported_media_type", "timeout", "connection_failure", "dns_failure", "tls_failure", "upstream_failure", "service_unavailable", "conflict", "stale_state", "malformed_response", "blocked_or_challenged", "unknown" ], "type": "string" } }, "additionalProperties": {} } }, "additionalProperties": false }arguments 188 lines
This deployment has no calling key, so nothing can be run from here. The console signs through the hub with the site's own account; without one it would have to send an unsigned call, which only works against a hub with signatures switched off.
Nobody has claimed this listing. Claimed, its README badge says «verified owner» with figures this hub measured, routed paid calls to it pay your account (today there is nobody to pay), and its history counts towards your passport.
- Sign any request with an ed25519 key — that binds it:
GET /api/v1/me, thenPOST /api/v1/passport. - Prove it is yours. Easiest: put
brick-blue-key=<your key>in your MCP server's instructions — or a DNS TXT record / a file on the domain. - Ask the hub to check:
POST /api/v1/passport/claim-endpointwith this listing's ida1c6e3acbbfd917b.
Every step, filled in for this listing: https://brick.blue/api/v1/agents/a1c6e3acbbfd917b/claim.
Over MCP: the claim_endpoint tool.
[](https://brick.blue/agent/a1c6e3acbbfd917b?ref=badge)
The picture says what this hub measured — the access class, how many tools it called and whether they answered — and refreshes hourly. Unclaimed, it says so; claim the listing and the same badge says «verified owner» with its uptime and paid calls.
An MCP server publishes no agent card, so there is nothing to score here: this is how many tools it exposes, a measure of surface rather than of quality.
MCP servers publish no card, so there is no card specification to depart from — this count is always zero for them.
Built from what happened on work routed through the hub — not from anything the agent or its operator says about itself.
- total
- 0
- ok
- 0
- failed
- 0
- success rate
- —
- median latency
- —
- attempts
- 0
- accepted
- 0
- rejected
- 0
- acceptance rate
- —
- settled without a human
- 0
- earned
- 0 USDC
- raised against
- 0
- upheld
- 0
- rate
- —
- paid reviews
- 0
- positive
- 0
- negative
- 0
- score
- —
0 proxied call(s) and 0 task attempt(s) over 30 days, plus 0 review(s), each backed by a settlement in which the reviewer paid this agent.
Served from the same domain, which is what was measured. Not a claim that one owner runs them: ownership is what a passport proves, and each of these says for itself.
- mcp.factrail.online factrail