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

'Set or change' hints that an existing category is overwritten, which is consistent with destructiveHint=true, and the confirmation gate is useful operational context. With annotations already covering readOnly/destructive/idempotent semantics, the remaining gaps (what happens to the prior category, whether category_id must pre-exist, error behavior) keep this at a 3.

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, and the preconditions are front-loaded after the action statement. Nothing is wasted, though the brevity leaves the coverage gaps noted above.

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 with annotations, no output schema, and 4 parameters, the definition conveys the mutation plus its confirmation gate, which is the minimum an agent needs to call it. It stops short on failure modes, category validation, and the idempotency behavior that the schema flags but the description never reinforces.

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 50%, and the half that is documented (confirmation, idempotencyKey) is already fully described in the schema; the description merely repeats the confirmation flag. The two core parameters, transaction_id and category_id, get no added meaning such as whether category_id must reference an existing category or accept special values.

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 ('Set or change') and resource ('the category of a transaction'), which is unambiguous standalone. It does not, however, distinguish itself from update_transaction, which plausibly also touches a transaction's fields, so sibling differentiation is missing.

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 only guidance is a precondition ('Requires confirmation: true to execute'), which is a gate rather than a when-to-use rule. Nothing says when to pick this over update_transaction or how it relates to create_category when the desired category doesn't exist.

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