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

With annotations covering the safety profile (readOnly=false, destructive=false, openWorld=true), the description still adds substantial behavior: the server downloads and re-hosts the file, format is validated from bytes not headers, the returned media id is meant to be passed to publish, and each channel applies its own format check at publish time.

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?

Front-loaded with the action and the payoff ('attach... we give you a media id you can pass to publish'), then constraints, then formats, then the altText cue. No filler sentences; every clause carries actionable information.

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?

No output schema exists, yet the description explains what comes back (a media id for publish) and how formats/channels interact. For a 4-param, one-required tool with a single remote input, nothing an agent needs to invoke it correctly is missing.

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%, so the baseline is 3. The description adds real value beyond it: url must be a direct file URL ending in the file itself, accepted MIME list, and the cue that altText should be written whenever the image is visible. It does not elaborate on aiGenerated or workspaceId beyond the schema.

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 precise verb+resource: attach already-hosted media by URL, with the mechanism spelled out (we download it, copy it into storage, return a media id). It clearly positions itself against the upload-style siblings (media_presign/media_upload_link) by saying 'no upload needed'.

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 strong usage conditions and exclusions: https only, Google Drive/Dropbox share links return HTML and won't work, use a direct file URL. It does not name a specific sibling tool to use instead when the URL is a local/private asset, so it stops short of explicit alternative routing.

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