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

Beyond the readOnly/idempotent annotations, it discloses the failure mode (precondition error when audio is not ready), the auth requirements (narrador:files OAuth scope or nrd_files_* API key), and field-level nullability (duration may be null). This is real behavioral context an agent needs before calling.

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?

Front-loaded with purpose then return shape, with prerequisites and auth at the end. The enumeration of return fields is justified since no output schema exists, though 'Read-only operation' overlaps the annotations and is slightly redundant.

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 fully specifies the return payload (jobId, audioUrl, audioId, duration, wordTimings and their sub-fields), plus preconditions and auth. An agent has everything needed to call and interpret this tool correctly.

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 only one parameter, so the schema already documents jobId fully. The description's mention of jobId comes in the context of return values rather than adding input semantics, so the baseline 3 applies.

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 ('Fetches completed narrador files job audio and metadata') and names the exact payload returned. It is clearly distinguishable from the sibling get_files_job, which only reports job state.

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?

Gives an explicit precondition ('Only succeeds when job status is completed') and an explicit alternative to call first ('Call get_files_job first to confirm the job is completed'). Nothing is left to inference about when to invoke this tool.

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