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

Annotations indicate readOnlyHint=false, destructiveHint=false, idempotentHint=false, but the description adds meaningful behavioral context: the upload is private, the URL is expiring, and the service verifies ownership/type/size/completion before attaching. It also implies a two-step process (upload then attach), which is valuable beyond the annotations. Minor gap: it doesn't explicitly state that the upload URL is single-use or what happens on failure, but the provided context is strong.

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 three sentences, each earning its place: what the tool returns, what the agent must do next, and what the service verifies. It is front-loaded with the core purpose and avoids redundancy with the schema.

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 tool has an output schema (not shown in the prompt but indicated as present), and the description covers the workflow, verification behavior, and next steps. It doesn't explicitly mention error cases or rate limits, but for a preparation step with a clear follow-on action, it is nearly complete. The only notable omission is guidance on handling the expiring URL (e.g., time-to-live), but this is minor.

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 schema already documents all four parameters. The description adds context about the upload flow but doesn't add new parameter-level semantics beyond what the schema provides. Baseline 3 is appropriate because the schema carries the parameter documentation burden.

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: preparing a private upload for a reply attachment, returning a signed PUT URL and headers, and instructing the agent to upload bytes and pass upload_id to reply_to_comment. This distinguishes it from siblings like reply_to_comment and create_comment by focusing on the upload preparation 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?

The description explicitly explains the workflow: call this tool to get the upload URL, upload the file bytes, then pass upload_id to reply_to_comment. It also notes that the service verifies ownership, type, size, and upload completion before attaching, which clarifies the expected sequence and prerequisites. This is strong guidance for when to use this tool versus alternatives.

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