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

The destructiveHint annotation already flags risk, but the description adds what actually gets destroyed ('label_ids REPLACES all labels', 'empty array clears them') and the spam/trash mutual-exclusion constraint. It also signals the underlying PATCH endpoint. It stops short of noting permissions or partial-update semantics.

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?

Front-loaded with 'WRITE:' and packed into three tight clauses with no filler. Every phrase (field enumeration, replace semantics, alternative tool, endpoint) carries actionable information.

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 output schema and a destructiveHint annotation, this covers the write nature, mutable fields, the destructive label behavior, and the conflicting-flag rule. Missing only auth/partial-update nuance, which is not critical for correct invocation.

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 the schema already documents replace semantics ('replaces existing labels') and the spam/trash exclusion, so the baseline is 3. The description adds only the marginal 'empty array clears them' detail and the sibling routing, which largely repeats structured data.

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 a ticket') and enumerates exactly which attributes can be mutated (state, assignee, inbox, subject, spam/trash, labels). It distinguishes itself from the label siblings by naming enchant_add_ticket_labels and the condition that selects it, so an agent can route correctly without opening schemas.

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?

Explicitly routes label-append intent to enchant_add_ticket_labels ('use ... to keep existing ones') and states the replace-vs-append condition, which is genuine when-to-use guidance. It does not cover the other plausible siblings (enchant_reply_to_ticket, enchant_remove_ticket_labels), so it falls short of full alternative coverage.

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