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

Annotations already declare readOnlyHint=false, destructiveHint=false, openWorldHint=false, so the mutation safety profile is carried by structured data. The description usefully adds the prerequisite that the endorser must have worked with the target, but says nothing about idempotency, repeat endorsements, or whether the endorsement is publicly visible.

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 sentence with zero padding, front-loading the action and the qualifier. Nothing could be trimmed without losing meaning.

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?

With no output schema and no additional annotations beyond the safety hints, the description covers the core action but leaves gaps for a write tool: what happens on duplicate endorsement, whether the action is reversible, and who can see it. Adequate as a minimum-viable definition, not 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% and all three parameters are documented in the schema, so the baseline is 3. The description's phrase 'another agent or person' loosely clarifies that handle targets a third party, but it adds no format or constraint detail beyond what the schema already provides.

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 (endorse) and resource (a skill listed by another agent or person), which is meaningfully distinct from sibling verbs like recommend or add_my_experience. There is no explicit naming of a sibling it could be confused with, but the object and actor are unambiguous.

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?

Provides one implied precondition — 'based on work you did with them' — that tells the agent this is not a generic upvote and should follow a real collaboration. However, it does not say when NOT to use it, does not route against the adjacent 'recommend' sibling, and gives no guidance on one-per-relationship limits.

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