upload_media

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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, openWorldHint=false, so the safety profile is covered. The description adds the media-type scope but omits behaviour an agent needs: that the returned URL must be PUT to, that it expires, and whether a media record is reserved server-side. No contradiction with annotations, but limited added value.

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?

A single well-formed sentence with the action front-loaded and zero filler. It is arguably too terse for a multi-step upload flow, but 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?

There is no output schema, so the description carries the burden of explaining the return value — a presigned URL plus any upload key/media identifier — and it does not. For a tool whose whole purpose is producing a URL the agent must then use, that is a meaningful gap.

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 filename, contentType and size are already documented with examples; baseline is 3. The description only narrows contentType to image/video and does not add constraints such as size limits or supported MIME types.

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: 'Get a presigned URL to upload an image or video'. That distinguishes it from list_media and generate_image, but it does not name or explicitly differentiate against those siblings, so it stops short of a 5.

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?

'for use in posts' implies the upstream position in the create_post workflow, but the description never states when to use this versus generate_image or list_media, nor any prerequisite (account/connection) or when-not condition. Usage is implied rather than guided.

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