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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=true), and the description is consistent with them. It adds the exact-match precondition, which is real behavioral context, but says nothing about failure behavior when the text is not found or what the call returns.

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, zero filler, with the action stated first and the critical constraint immediately after. Nothing wastes the agent's attention.

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 simple three-parameter mutation with no output schema, the description covers the core action and its key precondition, while annotations carry the safety and idempotency profile. The remaining gap — what happens when the text is absent or which errors surface — is minor.

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 baseline is 3, and the description adds meaning beyond the schema by specifying that 'text' must match the article content exactly — a constraint not present in the schema's generic 'text passage to highlight' wording.

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 ('Highlight') and resource ('a text passage in an article'), which cleanly distinguishes it from siblings like remove_highlight and get_highlights. It does not explicitly name an alternative, but the verb alone makes the intent 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?

The description supplies a hard precondition ('the text must exist exactly in the article content'), which is genuinely useful invocation guidance. However, it offers no when-to-use vs when-not guidance and never references the create/remove/read siblings, so usage is implied rather than stated.

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