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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the safety profile is covered; the description usefully adds the authentication and ownership preconditions. However, it never states the critical partial-update semantics — whether omitted fields like tags or is_public are left unchanged or cleared — nor what happens when the caller does not own the link. For an update tool with three optional mutable fields, that omission leaves real behavioral ambiguity.

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?

Two short sentences with no filler; the core action and the mutable fields come first, followed by the access precondition. Every clause carries information the agent needs.

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 tool is simple (one required param, five total), an output schema exists so return values need no explanation, and the description covers scope plus access requirements. The remaining gap is partial-update semantics and the role of the undocumented-in-description session_id, which keeps it just short of complete.

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 the schema already documents all five parameters including the accepted 'code or full short URL' format. The description only restates that title, tags, and visibility are updatable and adds no format, constraint, or edge-case detail beyond the schema, so the baseline of 3 applies.

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 ('Update an existing short link') and enumerates the mutable fields (title, category tags, public visibility), which lets an agent distinguish it from create_short_url and delete_short_url by implication. It stops short of naming a sibling or stating an explicit boundary, so it is clear but not maximally differentiated.

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 a prerequisite ('Requires the user to be authenticated and own the link') but no explicit when-to-use vs when-not guidance and no mention of the read-only alternatives like get_link_info that an agent might confuse this with. Usage is inferable from the verb but not spelled out.

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