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

The description goes well beyond annotations by disclosing that tags and regular_collection_names replace the existing set, that url is read-only, and that image_url updates are silently ignored unless handled through split_set_link_image. These are non-obvious behavioral details that materially affect correct invocation.

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 sentences, each earning its place: the first states the tool's purpose, the second provides critical replace-not-delta semantics, and the third routes image changes to the correct sibling. No filler or repetition.

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?

The description is thorough for a mutation tool with no output schema and strong annotations: it covers replace semantics, read-only fields, and the image alternative. The primary gap is the unmentioned `is_favourite` parameter, which an agent might not realize is updateable through this endpoint.

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 only 20%, so the description must compensate. It does for `name` (title), `tags` (replace semantics), and `regular_collection_names` (full desired list). It does not explain `is_favourite`, a non-obvious boolean parameter, and `uuid` is only implied as the link identifier.

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?

The description clearly states the tool updates a link's title, tags, or collection membership with a specific verb and resource. It differentiates from split_set_link_image by noting image changes must go through that sibling. However, it omits the updateable `is_favourite` parameter, so the stated purpose is not fully complete.

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?

The description gives explicit alternative guidance for changing the card image: use split_set_link_image rather than PATCHing image_url, which is silently ignored. It does not discuss when to prefer this tool over other link-related operations, but the image-specific routing is clear and useful.

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