apply_annotation_update

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

With no annotations, the description carries the full behavioral burden. It discloses meaningful safety constraints (user approval required, fingerprint freshness, do not use shell commands to delete or reconstruct the PDF), but says nothing about reversibility, side effects on other annotations, or failure modes when the fingerprint is stale.

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 lines, front-loaded with the core action, then prerequisites, then the safety prohibition. Every sentence earns its place and nothing is 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?

For a mutation tool with no annotations, no output schema, and 0% schema coverage across six parameters, the description covers workflow and safety but leaves parameter meaning and post-call effects unaddressed. Adequate on workflow, incomplete on invocation detail.

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 0%, so the description must explain six undocumented parameters. It only gestures at expected_fingerprint ('fresh fingerprint') and the file prerequisite ('*-annotated.pdf copy'); xref, page, color, and opacity are left entirely unexplained.

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 ('Change ONE existing highlight'), and the qualifiers 'ONE' and 'existing' implicitly separate this from the create-oriented apply_highlight and the propose_* siblings. It stops short of naming an alternative outright, so it is clear but not maximally differentiating.

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?

Gives a clear precondition for use ('after explicit user approval') plus setup requirements, a fresh fingerprint and an existing *-annotated.pdf copy. It does not explicitly route the agent to propose_annotation_update versus apply_annotation_update, so guidance is strong but not complete.

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