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

The description asserts 'Idempotent: re-posting the same terms reports them as already_tracked instead of creating duplicates', but the annotations declare idempotentHint=false, which says repeated identical calls do have additional effects. This directly contradicts the structured hint. The remaining behavioral detail (plan caps, per-keyword outcomes, auth requirements) is genuinely useful, but the contradiction is the dominant signal here.

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?

Front-loaded with the write designation and the core action, then layers requirements and limits. Every sentence earns its place, though the single dense block of five ideas could be broken up slightly for scanability.

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?

With no output schema, the description compensates by describing the return shape (per-keyword created / already_tracked / failed), the partial-success behavior at plan caps, and the required plan and auth scope. Nothing essential to invoking it correctly is missing.

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%, and the schema already documents app_id's origin, the country default, and the 1-200 keyword bounds. The description adds only that duplicates/already-tracked terms are reported rather than duplicated, which is behavior rather than parameter syntax, 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 and resource ('starts daily rank tracking for one or more keywords on an app') plus the write nature, which cleanly separates it from read-side siblings like sonar_app_keywords and from sonar_untrack_keywords/sonar_star_keyword. An agent can identify the operation without opening the schema.

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?

Gives clear preconditions for use: an Indie plan, an authorized Sonar account or API key with write scope, and the consequences of hitting the plan cap. It never names a sibling alternative (e.g., when to prefer star_keyword or app_keywords extraction over tracking), so it is strong context without explicit exclusions.

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