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

With no annotations, the description carries the burden and discloses key behaviors: only entries where the authorized-seller set changed are included, results are newest first, and `since` bounds `observed_at`. This adds useful context beyond the raw schema.

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?

Structured efficiently: first paragraph states purpose and context, then parameter list, then return format. Each sentence adds necessary information without redundancy.

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?

Given no output schema and no annotations, the description fully covers parameter semantics, return structure (`changes[]` with fields), and usage context. It is self-sufficient for an agent to invoke and interpret results.

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?

Despite 0% schema coverage, the description fully explains all three parameters: `domain` as required path parameter, `since` as ISO date-time lower bound on `observed_at`, and `limit` with default and maximum. This exceeds what the schema alone provides.

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 the tool returns a publisher's ads.txt change log, with the verb 'Returns' and a specific resource. It distinguishes itself from sibling verification tools by focusing on historical changes and fraud auditing.

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 'this is how a buyer audits supply over time' provides clear context for when to use the tool, implying historical analysis rather than current-state verification. It does not explicitly name alternatives or exclusions, but the intent is clear.

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