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

The annotations already declare readOnlyHint=true, so the description need not repeat that. It aligns with the annotation by saying 'Fetch' and adds the API endpoint, but does not disclose return format, error behavior, or any additional side effects. This is adequate but not rich.

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 short, focused sentences. The first sentence front-loads the primary purpose, and the second adds the concrete API endpoint without unnecessary elaboration.

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 one-parameter, read-only tool, the description is sufficient. It tells what the tool does, the API endpoint, and the required ID, while the schema and annotations cover the parameter and safety profile. No output schema exists, but 'Fetch a single audience' adequately indicates the return concept.

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 input schema has 100% coverage with the parameter audience_id described as 'Audience id.' The description adds no new semantic meaning beyond restating that the lookup is by ID, so it does not exceed the baseline for high schema coverage.

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 uses a specific verb ('Fetch') and resource ('a single audience by id'), clearly distinguishing it from sibling tools like bird_list_audiences and bird_create_audience. The phrase 'by id' establishes the exact scope of the operation.

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 makes clear that this tool is for fetching one specific audience when an audience_id is available, which implies when to use it versus listing audiences. However, it does not explicitly name an alternative or state when not to use it, such as 'use bird_list_audiences to get all audiences.'

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