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

readOnlyHint=true already establishes this as a safe read. The description adds only the underlying REST endpoint (GET /calls/search), which is mildly useful provenance but discloses nothing about result shape, pagination behavior beyond the schema, or matching semantics (substring vs exact).

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?

Two short sentences, front-loaded with the core action and examples. The trailing REST endpoint reference is slightly extraneous but does not bloat the definition; nothing is wasted at length.

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?

No output schema exists, yet for a simple read-only search tool the definition covers the action, the searchable fields, and a safe read signal from annotations. An agent has enough to call it correctly. Actually, no output shape is described, which slightly under-serves an agent expecting structured results.

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 q, page, and per_page are already fully documented in the schema; the baseline is 3. The description's examples of what can be searched (phone number, tag, direction) add modest value about the q parameter's semantics but no syntax detail beyond the 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 states a specific verb and resource (search calls) and clarifies the search surface with examples (phone number, tag, direction). It does not explicitly differentiate itself from the sibling aircall_list_calls, so an agent must infer the search-vs-list boundary.

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?

Usage is implied by the term 'Search' and the example search keys, but there is no explicit guidance on when to prefer this over aircall_list_calls or the get_call* siblings, nor any stated prerequisites or exclusions. Adequate but leaves routing inference to the agent.

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