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

Annotations cover readOnly and non-idempotency, but the description adds real behavioral context: the full status lifecycle (dialing, in_progress, done, failed, no_answer, busy), the fact that summary/transcript/collected data only appear once the call has ended, and that recording_url expires after one hour — which also explains the idempotentHint=false. It does not mention auth or rate limits, but the operational detail is strong.

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?

A single front-loaded sentence that leads with the verb and resource, then lists returns without padding. Every clause earns its place.

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 return-field enumeration is somewhat redundant, but it usefully surfaces the status enum values and the conditional availability of fields. Prerequisites and lifecycle are covered; only the sibling-tool routing 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% and there is a single parameter, so the schema already documents call_ref. The description adds only that the ref originates from wa_ai_call_start, which is minor redundancy; baseline 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?

States a specific verb (Read) and resource (AI call) and enumerates the substantive return fields, so the agent knows exactly what it retrieves. The phrase 'started with wa_ai_call_start' situates it relative to the sibling that creates calls.

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 prerequisite is implied ('started with wa_ai_call_start', call_ref 'from wa_ai_call_start'), which gives usable context. However, it never contrasts with the sibling wa_ai_list_calls or states when to prefer this single-call fetch over the list tool, so usage is only implied.

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