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

Annotations already declare `readOnlyHint: true`, so the safety profile is covered. The description adds real behavioral context by listing the returned details (numbers, users, status, duration, notes, voicemail and recording ids, AI insights) and naming the underlying API endpoint, which helps the agent understand the response shape even without an output schema.

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 compact sentences with no wasted wording. The core purpose and id source are front-loaded, followed by return-field details and the endpoint.

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?

For a simple single-parameter read tool, the description provides the essential purpose, id source, return contents, and endpoint. It does not mention not-found behavior or invalid-id handling, but with read-only annotations and a fully documented schema, nothing critical is missing for correct invocation.

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 coverage is 100% and the parameter is already documented as the call detail record id. The description adds meaningful provenance by tying it to the `id` field returned by `rinkel_list_calls`, which is more useful than repeating the schema text alone.

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 - get one call detail record - and identifies the exact id provenance (`id` field from `rinkel_list_calls`). It implicitly distinguishes itself from `rinkel_get_call_by_network_id` by specifying the Rinkel id rather than a network 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?

It clearly explains where to get the required id (`rinkel_list_calls`) and what the tool retrieves, giving an agent enough context to use it correctly. It stops short of explicitly contrasting with alternatives like `rinkel_get_call_by_network_id` or `rinkel_get_call_transcription`, so it lacks full when/when-not guidance.

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