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

Annotations already mark this as a non-read-only, idempotent, non-destructive, open-world mutation, but the description adds real behavioral context beyond them: partial-update semantics ('Only the fields you pass are changed'), the side effect that showOnly silently switches the link to snapshot rendering with a 300 s default refresh, the refusal case, and the `media.edit` permission requirement.

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?

Dense and front-loaded: capabilities first, then the showOnly caveat, then side effects, then alternatives and permissions. Almost every sentence carries actionable information, though the run is long enough that the snapshot/refresh side effect could be tightened into a shorter clause.

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 6-parameter mutation tool with an output schema, everything an agent needs is present: partial-update behavior, the snapshot-rendering side effect and its default refresh, the media-type restriction, the required scope, and pointers to the preview and rename siblings. Return values are rightly left to the output schema.

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, but the description adds genuine meaning: showOnly takes a CSS selector, empty string restores the full page, and ids should be preferred over class names because republishing changes classes. It does not add anything beyond the schema for renderWidth/renderHeight/refreshSeconds/autoScrollPxPerSec.

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?

Specific verb (change how a web link renders) plus an enumeration of the exact renderable aspects (cropping, auto-scroll, refresh cadence, viewport size). It also names the siblings it is not — render_web_link for previewing and update_media for name/tags/folder — so an agent can disambiguate without opening the schemas.

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 routing: 'Then use render_web_link to see the result now; for name, tags or folder use update_media.' It also states the precondition that cropping requires a server-rendered snapshot and that the tool is refused for non-web-link media, so the when/when-not conditions are fully covered.

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