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

Annotations already declare readOnlyHint=false, and the description reinforces this with 'WRITES DATA'. It adds the specific behavior of returning a presigned PUT URL, which is helpful. However, it does not disclose that the URL is temporary or that the actual file upload must be performed separately via a subsequent PUT request—a critical behavioral detail for correct usage. The description is consistent with annotations but does not go far beyond them.

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 short but contains redundancy: 'WRITES DATA' and 'Creates or changes data in the workspace' say essentially the same thing. The essential information—'Register an upload slot and return a presigned PUT URL'—is present but not front-loaded; it appears after the redundant write warning. A more concise version would merge the write hints and lead with the core action.

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 only three optional parameters and no output schema, the description covers the basic purpose and return value (a presigned PUT URL). However, it omits practical details that an agent would need, such as the URL's expiration, the need to perform a PUT request separately, or any size/type restrictions. These omissions could lead to incorrect invocation, so the description is only minimally complete.

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?

The input schema provides complete descriptions for all three parameters (filename, file_name, content_type), including aliases and defaults. The tool description adds no additional meaning or constraints beyond what the schema already documents. With 100% schema coverage, the baseline of 3 applies.

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 clearly states the tool's purpose: to register an upload slot and return a presigned PUT URL. It uses specific verbs and a resource, distinguishing it from siblings like po_documents_create_from_content (which creates from content directly) and po_documents_get (which retrieves documents). The action is unambiguous.

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 provides no guidance on when to use this tool versus alternatives such as po_documents_create_from_content or other upload methods. It does not mention prerequisites (e.g., needing a workspace or folder context) or scenarios where a presigned URL is the appropriate choice. An agent is left to infer usage from the tool name and sibling list.

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