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

No annotations are provided, so the description carries the behavioral burden. It explains the two-step workflow, size limit, allowed file types, Bearer authentication for the PUT, and the terminal requirement. It does not mention reservation expiry, cleanup, or exactly how the token parameter is used, but the core behavior is clear.

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?

Two concise sentences, with the primary action and constraint front-loaded, followed by a useful fallback note. Every sentence contributes value and there is no repetition of schema or annotation content.

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?

The description provides the necessary workflow, upload URL reference, file constraints, and alternatives. Since there is no output schema, it would be stronger if it explicitly stated that the response contains upload_url, but the phrase 'then PUT the bytes to upload_url' makes that reasonably discoverable.

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 0%, so the description must compensate for documenting the three parameters. It indirectly hints at media_type via file types and at token via 'with Bearer', but it never explicitly maps token, filename, or media_type to their roles. An agent would still have to infer parameter semantics.

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 ('Reserve') and clearly states the resource and scope: a file slot for PDF, Excel, or image files up to 10MB, followed by a PUT to upload_url. It also explicitly distinguishes itself from send_file and upload_file, so an agent can tell it apart without opening the schema.

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 an explicit usage condition: use this tool when you have a terminal or HTTP client, since bytes must be PUT to upload_url afterward. It also names alternatives ('send_file or upload_file with a url, or content_base64') for cases without a terminal, which is clear routing guidance.

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