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

Annotations declare a non-readonly, non-idempotent write (readOnlyHint=false, idempotentHint=false). The description adds real value beyond that: it reveals the two-phase async behavior (response yields upload_url, a PUT is required, and audio is only attached after calling the complete API). It omits auth requirements and failure/retry behavior.

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?

Three sentences, purpose front-loaded, followed by the procedural steps. Every sentence is relevant to correct invocation, though the workflow sentences could be tightened.

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 an output schema present, return values need not be explained, and the description covers the purpose, the multi-step workflow, and the required follow-up call. It is complete enough to invoke correctly, missing only edge-case handling.

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%, so the schema already documents asset_ID and language_codes (including the ISO 639-1 reference). The description adds no syntax or format detail beyond the schema, so the baseline of 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: 'Add any audio file to the video asset.' It also distinguishes itself from the sibling complete_audio_upload by explicitly naming the 'audio upload complete API' as the required next step, so an agent can tell the two apart.

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 gives a clear sequencing context: call this, PUT files to the returned URLs, then call the audio upload complete API. This routes the agent correctly through the workflow, though it never states when this tool should NOT be used or what happens if the workflow is abandoned.

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