Initialize document upload

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

With annotations only covering safety hints, the description carries the real behavioral burden and does so: it warns that the URL signs content-type and host only, that any x-amz-* header (especially SDK checksum headers) invalidates the signature, and that the contentType must match. It also discloses the required projects:write scope. This is exactly the kind of non-obvious operational detail an agent cannot infer from schema or annotations.

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 tightly written sentences, front-loaded with the return values, followed by the critical header caveat and the next-step call. Every sentence carries actionable information with no filler.

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?

Although there is no output schema, the description names the return fields and the complete two-step upload flow, so an agent knows both what it gets back and what to do next. Nothing essential for a correct invocation 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 coverage is 67% (projectPid is undocumented), so the description must compensate, and it does: it ties contentType to the signed PUT header, which is the semantically important constraint. It adds meaning beyond the schema, though projectPid's role remains unexplained.

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 verb and resource (start a presigned upload) and names the concrete artifacts it returns (uploadUrl and s3Key). It is clearly distinguishable from the sibling air_upload_document_complete, which it explicitly references as the follow-up step.

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?

It gives a clear workflow context: upload first, then call air_upload_document_complete with the returned s3Key, and it names the required scope (projects:write). It does not, however, state when this tool should NOT be used or how it relates to any alternative upload path.

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