fathom-fyi

rotate_api_key

Generate a new API key for Fathom financial intelligence, deactivate the old key, and return the new value for updating MCP configuration.

Instructions

Rotate your Fathom API key. Generates a new key, deactivates the old one, and returns the new key. The user must update their MCP config with the new key. Max 3 rotations per day. Requires Starter tier or above.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "rotate_api_key"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv4.5.1Mar 25, 2026

TDQS

A4.7/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries full burden. It excellently discloses destructive behavior ('deactivates the old one'), side effects (invalidates previous key), output ('returns the new key'), rate limits, and tier requirements. Comprehensive for a mutation operation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Five sentences, zero waste. Front-loaded with the core action, followed by mechanics, user obligations, limits, and requirements. Every sentence provides essential information not available in structured fields.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite no output schema, the description explicitly states what gets returned ('returns the new key'). Covers prerequisites, side effects, and operational constraints, making it complete for a credential rotation tool with no parameters.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Input schema has 0 parameters. Per rubric, 0 params = baseline 4. The description correctly focuses on operation mechanics rather than inventing unnecessary parameter documentation.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses the specific verb 'Rotate' with the resource 'Fathom API key' and clearly distinguishes from siblings (all data retrieval/analysis tools). It further clarifies the mechanics: 'Generates a new key, deactivates the old one, and returns the new key'.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides clear prerequisites ('Requires Starter tier or above'), rate limits ('Max 3 rotations per day'), and critical post-action requirements ('The user must update their MCP config with the new key'). Lacks explicit 'when-not-to-use' or named sibling alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.