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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, covering the safety profile. The description adds valuable behavioral context by noting the URL is 'short-lived' and the blob id is 'signed', and that the upload goes directly to storage. It does not mention rate limits or error conditions, but this is reasonable given the annotation coverage.

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 a single, front-loaded sentence that efficiently conveys the tool's purpose and key outputs. Every phrase adds value without redundancy.

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?

Given the fully documented schema and existing annotations, the description provides sufficient context: what the tool returns (URL and blob id), their short-lived nature, and their intended use. It does not explain how to use the URL (e.g., HTTP method) or detail error cases, but these are minor gaps for a tool with rich structured data.

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 all parameters are already documented in the schema. The description does not add any parameter-level semantics beyond what the schema provides, which is the baseline expectation for high coverage.

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 ('Returns') and two specific resources ('short-lived URL' and 'signed blob id'), and clarifies their purpose: uploading a file directly to storage and attaching it to a piece or message. This distinguishes it from sibling tools like AddAttachmentTool, which likely consumes the blob id rather than producing it.

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 implies when to use the tool (you need an upload URL and blob id) but does not explicitly state when to use it versus alternatives, nor does it mention prerequisites or exclusions. The usage context is only implied by the stated purpose.

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