search_calls_by_number

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

With no annotations, the description carries full responsibility. It discloses normalization, last-10-digit matching, auto-resolution of account_id, and a constraints (7-digit minimum). However, it does not explicitly state it is read-only, though that is implied by 'Find calls'.

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 a bit verbose with the Args list, but it is well-structured and front-loaded with the core behavior. Every sentence adds value, so it is acceptable despite some wordiness.

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?

The description covers parameter behavior well. Given that an output schema exists, it is not required to describe return values. Missing info like pagination or result ordering is not critical for this search tool.

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 0%, so the description must compensate. It does so thoroughly: phone_number normalization and length constraint, account_id auto-resolve, company_id optional filter, days default. Adds significant value beyond the bare schema.

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 finds calls from/to a specific phone number, using a specific matching mechanism (last 10 digits). This distinguishes it from siblings like list_calls (all calls) or get_call (single call by ID).

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 does not explicitly mention when to use this tool versus alternatives like list_calls or get_call. It implies usage for phone number search but lacks contrast with siblings, which would help an agent decide between tools.

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