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

Annotations already say the tool is write-capable, idempotent, non-destructive, and not open-world. The description adds behavior beyond that: tracking is recurring daily, not a one-time action, and it explains partial-failure semantics so that terms exceeding the plan limit fail while the remaining terms are still added. It does not state the actual plan limit, but this is meaningful context 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 short sentences with zero filler. The core action is front-loaded, and the partial-failure rule follows as the one caveat that matters. Nothing important is buried or repeated.

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 three-parameter write tool with full schema coverage and no output schema, this is nearly complete. The one gap is that 'reported as failed' does not say what the caller receives, and the plan limit is referenced without a number. Those are minor for an agent deciding whether to call the tool.

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 description coverage is 100%, so the schema already documents terms, app_id, and country, including bounds and defaults. The description adds the idea of a per-plan term limit, which affects the meaning of the terms array, but does not refine parameter formats. That matches the baseline-3 case where the schema does most of the work.

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 and resource: 'Starts daily rank tracking' for 'App Store searches' for a tracked app. This clearly separates it from read-only siblings like search_app_store or suggest_keywords, though it never names the reverse operation untrack_keyword or distinguishes itself from track_app.

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 'for an app the user tracks' implies the prerequisite that the app must already be tracked via track_app, but that is left implicit. There is no explicit when-to-use or when-not-to-use guidance, and no alternative is named.

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