Begin attachment upload

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

With readOnlyHint=false, the agent already knows this mutates state, but the description does not disclose what this call actually creates, whether it returns an upload identifier, or that chunk upload and finish steps must follow. Saying 'Start' and 'client-neutral' adds only minimal behavioral context without covering side effects or lifecycle expectations.

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 short sentences with no filler. The first sentence states the purpose, and the second provides a high-value safety/usage constraint. Every word earns its place.

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?

This tool is clearly part of a multi-step upload flow alongside upload_attachment_chunk, finish_attachment_upload, and discard_attachment, but the description gives no sense of that sequence or what the caller must do after this step. An output schema exists, so return values are partially covered, but the workflow context is missing.

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 carry parameter meaning. It only clarifies filename ('never a local path'); content_type, size_bytes, and sha256_hex receive no explanation. This leaves three required parameters underdocumented.

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 specific action ('Start') on a specific resource ('attachment upload') and adds a scoping qualifier ('client-neutral'). It is clear enough to separate this from upload_attachment_chunk and finish_attachment_upload by the 'Start' verb, though it does not explicitly name those alternatives.

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?

'Start a client-neutral attachment upload' implies this is the initial step, and 'Pass a filename, never a local path' is a useful input rule. However, it does not explicitly state when to use this versus sibling upload tools, nor what prerequisites or follow-up calls are required.

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