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

Annotations already indicate this is not read-only and not destructive, so the description does not need to carry that burden. It adds the jobs:write scope and the ordering requirement, which is helpful context, but does not explain error behavior, idempotency, or what happens if parts are missing.

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 compact and front-loaded: purpose, body shape, timing, and auth scope each get only a short clause. The only structural concern is that 'then call /submit' reads awkwardly and could be misinterpreted.

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 tool with 3 required parameters and no output schema, the description is too thin on the complete invocation contract. The body snippet omits job_id while the schema requires it, and the relationship between this tool and /submit/submit_job is never clarified.

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 baseline is 3; the schema already documents job_id, upload_id, parts, part_number, and etag. The description's body example reinforces upload_id and parts but omits the required job_id, which risks confusion even though the schema is complete.

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 and resource, 'Assemble a chunked upload,' and includes the request body shape to clarify what the tool does. It is distinguishable from siblings like create_upload_url and submit_job, though it does not explicitly name them.

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 useful precondition: 'Only after every part has been PUT.' However, the follow-up 'then call /submit' is ambiguous about whether /submit is a separate step or part of this tool's flow, and it does not mention alternatives or when not to use the tool.

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