CPA: phone numbers from chats

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

Annotations already indicate read-only, non-destructive, idempotent, and open world behavior. The description reinforces with 'Read-only, spends no money' and adds important details: pagination and a rate limit of 5 requests/min. This adds value beyond annotations, though it doesn't describe error behavior or return format.

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 four short, focused sentences with no redundant information. It starts with the main purpose, then adds behavioral notes and usage context. Every sentence earns its place, making it efficient for an agent to parse.

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?

While the tool has low complexity (3 params) and annotations cover safety, the absence of an output schema means the description should clarify the return structure. 'Information on phone numbers' is vague; an agent may not know what fields are included (e.g., phone number, chat ID, timestamp). This gap reduces completeness despite clear purpose and usage.

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 coverage is 100% with each parameter already well-described (dateTimeFrom format, limit min/max, offset default). The description does not add extra semantic meaning to the parameters beyond what the schema already provides, so baseline of 3 is appropriate.

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 set of phone numbers extracted from CPA chats starting from a given moment. Verb 'returns' and resource 'phone numbers from target CPA chats' are specific and match the tool name. It distinguishes itself from sibling tools like cpa_chats_by_time_v1/v2 which likely retrieve full chat data without phone extraction.

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 explicitly says 'Use to export customer contacts from correspondence over a period,' providing clear usage context. However, it does not mention when not to use this tool or suggest alternatives (e.g., for full chat messages), which would improve guidance.

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