Fallback
Tiny paid recovery and decision utilities for autonomous agents.
Should I use this
Quality & Safety
A
Based on automated analysis of tool definitions and protocol compliance.
Context Cost
~1,882Tokens (tool definitions)
~4.3 KBTypical response size
Moderate attention impact (1.47% of 128k context)
This is the approximate number of tokens consumed each time the server's tools are loaded into a model's context. Higher counts reduce the attention available for other tasks.
Install
One-Click Install
Add this to your `claude_desktop_config.json` file:
{
"mcpServers": {
"fallback-agent-tools": {
"url": "https://fallback.factrail.online/mcp"
}
}
}Remote endpoints
https://fallback.factrail.online/mcpstreamable-httpWhat it can do
Tool inventory
Tools (4)
🟢 Read-only🟡 Write🔴 Delete⚪ Unknown
🟢source_route(goal, domain, start_url, preferred_formats, require_official, ...)
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: $0.02 USD per call via x402.
Input Schema
{
"type": "object",
"properties": {
"goal": {
"type": "string",
"minLength": 3,
"maxLength": 500
},
"domain": {
"type": "string",
"maxLength": 253,
"format": "hostname",
"pattern": "^(?=.{1,253}\\.?$)[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])?)*\\.?$"
},
"start_url": {
"type": "string",
"maxLength": 2048
},
"preferred_formats": {
"maxItems": 7,
"type": "array",
"items": {
"type": "string",
"enum": [
"json",
"csv",
"xml",
"rss",
"api",
"bulk_download",
"html"
]
}
},
"require_official": {
"default": false,
"type": "boolean"
},
"max_candidates": {
"default": 5,
"type": "integer",
"minimum": 1,
"maximum": 10
}
},
"required": [
"goal"
],
"$schema": "https://json-schema.org/draft/2020-12/schema",
"additionalProperties": false
}⚪error_route(goal, request, response, error, attempt)
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: $0.002 USD per call via x402.
Input Schema
{
"type": "object",
"properties": {
"goal": {
"type": "string",
"minLength": 1,
"maxLength": 500
},
"request": {
"type": "object",
"properties": {
"method": {
"type": "string",
"maxLength": 16
},
"url": {
"type": "string",
"maxLength": 2048
},
"headers": {
"type": "object",
"propertyNames": {
"type": "string",
"maxLength": 128
},
"additionalProperties": {
"type": "string",
"maxLength": 2048
}
},
"body": {}
},
"additionalProperties": false
},
"response": {
"type": "object",
"properties": {
"status": {
"type": "integer",
"minimum": 100,
"maximum": 599
},
"headers": {
"type": "object",
"propertyNames": {
"type": "string",
"maxLength": 128
},
"additionalProperties": {
"type": "string",
"maxLength": 2048
}
},
"body": {
"type": "string",
"maxLength": 8192
}
},
"additionalProperties": false
},
"error": {
"type": "string",
"maxLength": 2048
},
"attempt": {
"type": "integer",
"minimum": 1,
"maximum": 100
}
},
"$schema": "https://json-schema.org/draft/2020-12/schema",
"additionalProperties": false
}⚪request_repair(goal, request, response, error, error_route, ...)
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: $0.005 USD per call via x402.
Input Schema
{
"type": "object",
"properties": {
"goal": {
"type": "string",
"minLength": 1,
"maxLength": 500
},
"request": {
"type": "object",
"properties": {
"method": {
"type": "string",
"minLength": 1,
"maxLength": 16
},
"url": {
"type": "string",
"maxLength": 2048
},
"headers": {
"type": "object",
"propertyNames": {
"type": "string",
"maxLength": 128
},
"additionalProperties": {
"type": "string",
"maxLength": 4096
}
},
"query": {
"type": "object",
"propertyNames": {
"type": "string",
"maxLength": 128
},
"additionalProperties": {
"$ref": "#/$defs/__schema0"
}
},
"body": {
"$ref": "#/$defs/__schema0"
}
},
"additionalProperties": false
},
"response": {
"type": "object",
"properties": {
"status": {
"type": "integer",
"minimum": 100,
"maximum": 599
},
"headers": {
"type": "object",
"propertyNames": {
"type": "string",
"maxLength": 128
},
"additionalProperties": {
"type": "string",
"maxLength": 4096
}
},
"body": {
"$ref": "#/$defs/__schema0"
}
},
"additionalProperties": false
},
"error": {
"type": "string",
"maxLength": 4000
},
"error_route": {
"type": "object",
"properties": {
"classification": {
"type": "string",
"enum": [
"authentication_required",
"authorization_denied",
"rate_limited",
"quota_exhausted",
"payment_required",
"payment_failed",
"schema_mismatch",
"invalid_input",
"not_found",
"method_not_allowed",
"unsupported_media_type",
"timeout",
"connection_failure",
"dns_failure",
"tls_failure",
"upstream_failure",
"service_unavailable",
"conflict",
"stale_state",
"malformed_response",
"blocked_or_challenged",
"unknown"
]
},
"retry": {
"type": "string",
"enum": [
"never",
"immediate",
"after_delay",
"after_change",
"after_auth",
"after_payment",
"unknown"
]
}
},
"required": [
"classification"
],
"additionalProperties": {}
},
"schema": {
"$ref": "#/$defs/__schema0"
},
"constraints": {
"default": {
"allow_method_change": false,
"allow_url_change": false
},
"type": "object",
"properties": {
"allow_method_change": {
"default": false,
"type": "boolean"
},
"allow_url_change": {
"default": false,
"type": "boolean"
}
},
"additionalProperties": false
}
},
"required": [
"request"
],
"$schema": "https://json-schema.org/draft/2020-12/schema",
"additionalProperties": false,
"$defs": {
"__schema0": {
"anyOf": [
{
"type": "string",
"maxLength": 8192
},
{
"type": "number"
},
{
"type": "boolean"
},
{
"type": "null"
},
{
"maxItems": 256,
"type": "array",
"items": {
"$ref": "#/$defs/__schema0"
}
},
{
"type": "object",
"propertyNames": {
"type": "string",
"maxLength": 128
},
"additionalProperties": {
"$ref": "#/$defs/__schema0"
}
}
]
}
}
}🟢stop_search(goal, checks, remaining_routes, search_budget, risk)
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: $0.003 USD per call via x402.
Input Schema
{
"type": "object",
"properties": {
"goal": {
"type": "string",
"minLength": 1,
"maxLength": 500
},
"checks": {
"default": [],
"maxItems": 40,
"type": "array",
"items": {
"type": "object",
"properties": {
"target": {
"type": "string",
"minLength": 1,
"maxLength": 300
},
"method": {
"type": "string",
"enum": [
"direct",
"search",
"documentation",
"api_catalog",
"registry",
"browser",
"other"
]
},
"result": {
"type": "string",
"enum": [
"found",
"not_found",
"inconclusive",
"error",
"blocked",
"contradictory"
]
},
"authority": {
"type": "string",
"enum": [
"primary",
"official",
"secondary",
"general",
"unknown"
]
},
"coverage": {
"type": "string",
"enum": [
"low",
"medium",
"high"
]
},
"exhaustive": {
"default": false,
"type": "boolean"
},
"checked_at": {
"type": "string",
"format": "date-time",
"pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z|([+-](?:[01]\\d|2[0-3]):[0-5]\\d)))$"
}
},
"required": [
"target",
"method",
"result",
"authority",
"coverage"
],
"additionalProperties": false
}
},
"remaining_routes": {
"default": [],
"maxItems": 20,
"type": "array",
"items": {
"type": "object",
"properties": {
"route": {
"type": "string",
"minLength": 1,
"maxLength": 300
},
"expected_value": {
"anyOf": [
{
"type": "string",
"enum": [
"low",
"medium",
"high"
]
},
{
"type": "string",
"const": "unknown"
}
]
},
"estimated_cost_usd": {
"type": "number",
"minimum": 0,
"maximum": 10000
}
},
"required": [
"route",
"expected_value"
],
"additionalProperties": false
}
},
"search_budget": {
"type": "object",
"properties": {
"calls_used": {
"type": "integer",
"minimum": 0,
"maximum": 10000
},
"calls_remaining": {
"type": "integer",
"minimum": 0,
"maximum": 10000
},
"cost_used_usd": {
"type": "number",
"minimum": 0,
"maximum": 10000
},
"cost_remaining_usd": {
"type": "number",
"minimum": 0,
"maximum": 10000
}
},
"additionalProperties": false
},
"risk": {
"default": "medium",
"type": "string",
"enum": [
"low",
"medium",
"high"
]
}
},
"$schema": "https://json-schema.org/draft/2020-12/schema",
"additionalProperties": false
}Community
Evidence
Recent observations
verifiedversion not recorded4 tools