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

readOnlyHint=true already tells the agent this is a safe read. The description adds real value by disclosing that the response contains a download URL, which is not otherwise documented since there is no output schema. It omits whether the URL expires, requires auth, or is a redirect, which would be helpful for a download-oriented tool.

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 tight sentence with the key payload ('details and download URL') front-loaded and no filler. It is arguably too short for the gaps it leaves, but nothing in it is wasted.

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?

With no output schema, the description does minimal work to characterize the response ('details and download URL'), which is the right instinct. However, for a two-parameter tool where one parameter is undocumented and the returned URL's lifecycle is unstated, an agent is left guessing about acquisition of recordingId and URL validity.

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 only 50%: 'id' is documented as 'Call id.' but 'recordingId' has no description at all. The phrase 'one recording of a call' hints at the call-id/recording-id pairing, but the description never names or explains recordingId, so it does not compensate for the documentation gap.

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: 'Get the details and download URL of one recording of a call.' An agent can tell this is a single-recording fetch, and the mention of 'download URL' distinguishes it from siblings like spokephone_get_call or spokephone_get_transcript. It does not explicitly name those siblings, so it falls short of a 5.

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?

No statement of when to use this versus spokephone_get_call, spokephone_get_transcript, or spokephone_list_calls, and no note on how a recordingId is obtained or what to do if no recording exists. Usage is only inferable from the name and 'of one recording of a call'.

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