fetch

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description adds substantive content-level detail about what each variant returns (a keyword's current state and rank history, a rival's beaten keywords), 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?

Two sentences, front-loaded with the core purpose and then the payoff of the call. Efficient, though the second sentence listing return fields is close to verbose for a schema-free description.

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?

For a single-parameter read tool with full schema coverage and no output schema, the description covers what the id selects and roughly what comes back. No pagination or shape details, but annotations carry safety and the schema carries the param, so it is nearly complete.

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?

Schema coverage is 100% and the schema already documents the id format and prefix types (app:, kw:, rival:). The description reinforces that the id is 'from search' but adds little syntax beyond the schema, so the baseline 3 applies.

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?

States a specific verb ('fetch') and resource ('the full record behind one id from search'), then names the exact entity types returned (app card, tracked keyword, rival). This clearly distinguishes it from siblings like search, get_app, and get_keyword_metrics.

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 phrase 'one id from search' establishes the workflow context: this tool resolves ids that search returned. It does not explicitly name an alternative or state when-not, but the usage context is unambiguous for an agent that just ran search.

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