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

Adds substantial behavior beyond the annotations: what data moves (messages, notes, email threads, tags, fields), that future mail in the duplicate's thread reroutes to `into`, that `into` reopens if the duplicate was open, that the duplicate is resolved and linked, and that replies go only to `into`'s requester. It also discloses cost ($0.01 per call, free on failure), which annotations never cover.

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 verb, resource, and param roles; each subsequent clause carries new, actionable information (data moved, mail rerouting, reopen side effect, cost). No filler sentences.

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-param mutation with no output schema, the description covers side effects, downstream routing, and cost/failure pricing thoroughly. It does not state whether the merge is reversible, what permissions are needed, or what errors occur for self-merge or missing tickets.

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?

The schema gives both integer params an identical, ambiguous description ('The ticket number, e.g. 42 for ticket #42'), so the description's assignment of roles (number = duplicate being absorbed, into = surviving ticket) is the only source of disambiguation. It stops short of covering edge cases like self-merge or invalid numbers, so not a full 5.

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 (merge) and resource (duplicate ticket) plus the direction of the merge: `number` collapses into `into`. An agent can distinguish it from ticket_update, ticket_delete, and ticket_reply without opening any schema.

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 use case ('a duplicate ticket') is implied clearly, but there is no explicit when-to-use/when-not guidance and no alternative named (e.g., resolve a ticket via ticket_update instead of merging). The agent must infer the selection conditions.

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