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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds genuinely new behavior: polling cadence for the processing state and the meaning of an empty result. It does not discuss what happens if the sessionId is invalid or expired, which is the main remaining gap.

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?

Four short sentences, front-loaded with what it lists and scoped immediately, then status semantics. Every sentence adds information an agent needs to call it correctly; nothing is redundant.

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?

With an output schema present, return values need not be explained, and the description still covers the status lifecycle and readiness for post attachment. It is nearly complete; only session expiry/error handling is unaddressed.

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 100% and the schema's sessionId description already says "returned by uploadWidgetTool." The description restates that origin but adds no format, validation, or lifetime details beyond the schema, so baseline 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?

States a specific verb+resource+scope: lists media uploaded in a specific upload-widget session, keyed by sessionId. It explicitly distinguishes itself from the broader library listing ("not the whole media library"), which separates it from sibling mediaListTool.

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?

Gives concrete call conditions and follow-ups: empty list means nothing uploaded yet, "processing" means wait ~10 seconds and call again, "ready" means it can be used as a post attachment. It also ties the input to its producer (uploadWidgetTool), so the agent knows the prerequisite step.

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