partner_metrics_fetch

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe read operation. The description adds value by disclosing that a wrong body shape results in an HTTP 400 with a JSON-parse error, which goes beyond the annotations.

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

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

The description is well-structured: it starts with a clear purpose, then details the body shape, highlights important notes, mentions error behavior, and describes pagination. While slightly long, every sentence adds value and the critical information is front-loaded.

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

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

The description covers the body shape, error handling, and pagination, but does not describe the return value format. Since there is no output schema, the agent may lack understanding of what the response contains. The inclusion of a spec link partially compensates but does not fully address the gap.

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

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

The description provides extensive detail on the body parameter's shape, including nested objects, required fields, and specific constraints (e.g., 'metrics is an OBJECT, not an array'). This goes well beyond the schema's minimal description, especially since the body schema only has a generic reference.

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

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

The description clearly states 'Fetch partner-metric time series', specifying a concrete verb ('Fetch') and resource ('partner-metric time series'). This clearly distinguishes it from sibling tools like metrics_churn or metrics_conversion, which focus on specific metric categories.

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

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

The description explains how to use the tool (e.g., body shape, pagination) but does not provide guidance on when to choose this tool over alternatives. No explicit when-not-to-use or alternative tool references are given.

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