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

Annotations only supply destructiveHint=true, so the description usefully adds that this is a WRITE, that it is additive/partial (existing labels preserved), and the exact REST endpoint. It does not cover idempotency, auth/permission requirements, or what happens on invalid label ids, which is why it is not a 5.

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 operation type and the key behavioral constraint come first, followed by the API mapping. Every clause earns its place.

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 two-parameter mutation with an easy schema, no output schema, and annotations that only carry a destructive hint, the description covers operation type, partial-update semantics, and endpoint. Minor gaps such as permission requirements or error behavior remain, but nothing essential to invoking it correctly 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 description coverage is 100%, so both parameters are already documented ('Ticket id.', 'Label ids to add.'), which sets the baseline at 3. The description adds only the URL template mapping, not new meaning about formats or constraints beyond minItems=1.

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 (add), resource (labels), and target (ticket), and explicitly scopes the effect with 'without changing its other labels', which separates it from enchant_remove_ticket_labels and any label-replacement tool. The REST mapping reinforces exactly which operation is performed.

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 additive-semantics phrasing ('add ... without changing its other labels') implies when to reach for this tool rather than a replace or remove operation, and the sibling enchant_remove_ticket_labels makes the opposite case obvious. It stops short of explicitly naming the alternative or stating preconditions, so it falls short of a 5.

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