search_calls

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

With no annotations provided, the description carries the full burden. It discloses the return structure (rows plus pagination cursor) and clarifies the meaning of duration fields, explaining that CDR duration and TaskRouter talk time are never conflated. This goes beyond a simple search description and adds valuable behavioral context, though it omits details like authentication or rate limits.

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 action and scope, and every sentence contributes meaningful detail. It is concise with no filler words, and the structure effectively communicates purpose, return shape, and key nuances.

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 the tool has 10 parameters, no output schema, and no annotations, the description does a good job covering the essential usage context: what it filters on, that it returns rows and a pagination cursor, and that duration semantics are explicit. It could have described return fields in more detail, but the provided info is sufficient for an agent to select and invoke the tool reasonably.

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%, so the baseline is 3. The description adds a small amount of extra meaning by clarifying duration measurement semantics relevant to min_duration, but the schema already documents each parameter well. The added value is marginal but not absent.

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 searches and filters Twilio call records, listing the specific filter dimensions (date range, phone number, direction, etc.). It provides a specific verb and resource, but does not explicitly name sibling tools for differentiation, so it falls just short of a 5.

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 implies when to use the tool (searching and filtering call records) and what it returns (rows plus pagination cursor), but it does not explicitly state when not to use it or mention alternatives like get_call for a single call. This provides some context but no exclusions or alternative references.

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