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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, yet the description still adds real context: account-scoping, newest-first ordering, and the 90-day transcript retention window that limits what the transcript search can reach. It does not explain pagination behavior (no cursor/offset exists, limit caps at 50), which an agent retrieving many calls would need to know.

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?

Front-loaded with scope, ordering and returned fields, then use cases, then the alternative — a sensible information order. It wastes some space by asserting read-only twice ("Compliance: read-only" and a trailing "Read-only."), both redundant with the annotations.

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?

An output schema exists, so the field list is supporting rather than load-bearing, and the description still covers scope, retention limits, ordering, use cases and the detailed alternative. For a read-only, non-paginated listing tool, nothing an agent needs to call it correctly is missing.

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 limit, query and outcome are already fully documented in the schema, and the baseline applies. The description adds only an oblique hint about text search via the "garage" question example; it adds no syntax, default, or interaction details 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?

States a specific verb and resource ("List this account's calls"), specifies ordering ("newest first") and enumerates the returned fields (call_id, phone number, status, outcome, task, summary). It also names the sibling it is not — "For the full result and transcript of one call, use get_call" — so an agent can distinguish it without opening the schema.

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?

Gives three concrete use cases (find a call_id, check whether a number was already called recently, answer "what happened with my call to the garage?") and routes single-call detail work to get_call with a specific parameter value. It does not address the close sibling get_batch_calls or state when this tool should be avoided, so the exclusions are incomplete.

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