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

The annotations already indicate read-only, idempotent, and non-destructive behavior, and the description does not contradict this. It adds useful behavioral details about the URL expiring after 1 hour and the recording-enabled prerequisite, which go beyond the annotations and help the caller understand side effects and limitations.

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 concise and well-structured, with three short sentences that each convey essential information: the action and format, the expiration, and the prerequisite. There is no redundant or extraneous content.

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?

Given the simplicity of the tool (one parameter, no output schema displayed), the description sufficiently covers the key context: what is returned (a time-limited URL), the format, and a key condition for success. It does not describe error cases or response structure, but those are not essential for a straightforward get operation and would not significantly hinder 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?

The only parameter, id, is described in the schema as 'The call ID,' and the tool description does not add further semantic detail beyond that. Since schema coverage is 100% for the parameter, the baseline score of 3 is appropriate; the description does not need to elaborate further but also does not add extra value.

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 action (get a download URL), the resource (call recording), and the format (WAV), making the tool's purpose unambiguous. It also distinguishes the tool from related ones like phone_call_transcript_get by focusing on the recording URL rather than transcript content.

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 provides a prerequisite for use ('Recording must have been enabled during the call') and notes the URL is time-limited, which helps set expectations. However, it does not explicitly mention alternative tools or when to prefer this one over siblings like phone_call_get or phone_call_transcript_get, leaving some usage guidance implicit.

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