Mark underlines processed

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

Annotations declare it is a non-readonly, idempotent, non-destructive write; the description goes further by scoping the mutation (only pending red underlines, other colors skipped, never changed) and explicitly stating nothing is deleted. These details materially reduce the risk of unintended edits beyond what the annotations convey.

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 short sentences, front-loaded with the action and the side-effect warning before the precondition. Every sentence carries distinct information with no padding.

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 rich annotations, a full input schema, and an output schema present, the description supplies exactly what structured fields cannot: the approval prerequisite, mutation scope, and non-deletion guarantee. Nothing needed to invoke it safely is missing.

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 both parameters (ids, document_path) are already documented, including the source of ids and the default front-document behavior. The description's "by id" adds no syntax or format detail beyond the schema, so the baseline 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: recolor pending (red) underlines to gray by id. It is clearly distinguishable from siblings get_pending_underlines (read) and clear_processed (removal), and the title reinforces rather than restates the operation.

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?

"Only run after the reader has approved" gives an explicit precondition for invocation, which is meaningful for a mutation tool. It does not, however, name sibling alternatives or explain the relationship to clear_processed, leaving some routing inference to the agent.

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