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

Annotations only declare readOnlyHint=true, so the description adds real behavioral value: it discloses that the field is_processing gates downstream queue usability and describes a polling pattern. It surfaces that processing state is part of the return, which the agent couldn't infer from annotations alone.

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 tight sentences: identity of the resource, the polling workflow, and the endpoint mapping. The most actionable constraint (polling until processed) is front-loaded, and 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?

For a one-parameter read with no output schema, the description covers the key return field (processing state) and the operational trigger for calling it. There is no gap an agent needs filled to call this correctly.

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% and the single parameter is already documented as the storage UUID, so the schema does the heavy lifting. The description's 'by UUID' reinforces but adds no syntax or format detail beyond it, matching the baseline of 3.

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 and resource ('Get one media file by UUID') and names the returned scope ('including its processing state'), which cleanly separates it from sibling list_media. An agent can identify the operation without opening the schema.

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 explicit workflow guidance ('After an upload, poll this until is_processing is false') and a precondition for downstream use ('only usable in queues once processed'). It doesn't name list_media as the alternative for enumerating media, so it stops short of full when-not guidance.

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