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 safety profile is fully covered. The description adds minor behavioral context by stating it returns conversion data, but it does not disclose any additional traits such as rate-limiting, authentication specifics (beyond schema), or edge cases. It does not contradict the annotations, but the description's contribution to behavioral transparency is limited.

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 two sentences, front-loaded with the core purpose and returns. Every word adds information: the resource, the metrics, and the answerable question. There is no fluff or repetition of schema details. It is compact and efficient.

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 read-only analytics tool with high schema coverage and rich annotations, the description is largely complete. It lists the returned metrics and the core scope. It does not explain the return format or pagination, but since there is no output schema, the agent might need to infer structure. However, the purpose is sufficiently clear for successful invocation. Minor gaps around optional parameters (goal_id, segment) are covered by the schema, so the description is not lacking essential context.

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 86%, which is high, so the baseline is 3. The description adds no parameter-specific detail beyond what the schema already provides. It mentions 'for a site and period' but does not elaborate on date formats, segment syntax, or goal_id behavior. The schema already documents each parameter, so the description's marginal value here is minimal.

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 specifies the exact resource (Matomo goal conversions), the metrics returned (conversions, conversion rates, revenue), and the scope (site and period). It clearly differentiates from sibling Matomo tools like page_performance, referrer_breakdown, and visit_summary by focusing on goals. The phrase 'Answers which configured outcomes produced conversions and value' reinforces the purpose without ambiguity.

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 provides clear context for when this tool is appropriate: 'for a site and period' and specifically when you need goal conversion metrics. However, it does not explicitly mention alternatives or exclusion criteria, such as 'use matomo_visit_summary for general traffic analysis.' Since sibling tools are numerous but distinct, the implicit usage guidance is adequate but not fully explicit.

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