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

With no annotations provided, the description carries the full burden of behavioral disclosure and does so well. It reveals the returned fields (upload_url, s3_key, content_type), the required PUT request with exact Content-Type, the 6-hour link lifetime, and the 5 GB file limit. It also explains that the tool itself is not the upload step but the first step in a two-step workflow.

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 well-structured and front-loaded: it states the target scenario, the return values, the upload workflow with a concrete curl example, and the constraints. Every sentence contributes useful information, and the example is compact but instructive.

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?

There is no output schema, so the description appropriately explains the return values and the complete workflow required to use them. It covers prerequisites, the upload method, the Content-Type requirement, the expected next step, and constraints like expiry time and file size. An agent has enough information to successfully invoke the tool and complete the intended operation.

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 file_name and content_type in sufficient detail. The description adds contextual constraints like the local-file requirement and the 5 GB limit, but it does not substantially improve parameter-level semantics beyond what the schema already provides.

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 states a clear purpose: obtaining an upload URL for a local file that lacks a public link. It explicitly contrasts this with the public-link workflow by mentioning local files and routing the result to transcribe_file, which distinguishes it from siblings like transcribe_url.

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 clearly specifies when to use the tool: for a local file without a public link, and it outlines the follow-up step of passing s3_key to transcribe_file. It does not explicitly name the alternative for files with public links, such as transcribe_url, but the condition 'no public link' provides a clear contextual exclusion.

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