CPA: calls for a period

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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, destructiveHint=false. The description adds 'Read-only, spends no money' and mentions the rate limit, which are useful behavioral details beyond the annotations. It does not contradict 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?

The description is two sentences long, with the first sentence stating the core purpose and the second providing usage guidance. Every word earns its place; no fluff.

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 there is no output schema, the description mentions it returns a paginated list and that the results contain callId/actionId. It also includes the rate limit. While it doesn't detail pagination mechanics (like using offset vs max startTime), the parameter descriptions in the schema cover that. Overall, it is sufficiently complete for a list tool with well-covered annotations.

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?

The input schema already has 100% description coverage for all 3 parameters (dateTimeFrom, limit, offset). The description mentions 'by startTime' which reinforces the dateTimeFrom parameter, but adds no new details beyond the schema. Baseline score of 3 is appropriate as the description does not need to compensate.

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 it returns a paginated list of CPA calls filtered by startTime. The verb 'Returns' and resource 'CPA calls' are specified, and it distinguishes from sibling 'cpa_get_call_by_id_v2' by mentioning that the returned IDs can be used with it.

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?

Explicitly states when to use: 'Use to iterate over calls for a period'. It also gives a concrete workflow: the returned callId/actionId can be used with cpa_get_call_by_id_v2 or for filing a complaint. Additionally, it provides a rate limit warning (1 req/min), which helps the agent plan usage.

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