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

Beyond annotations (readOnlyHint=false), the description discloses a non-obvious side effect: recategorizing creates a Category Rule that affects future transactions. It also explains batch error semantics ('per-item errors do not fail the whole batch') and the override of Pluggy's automatic categorization.

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?

The description is dense but every sentence carries value: endpoint, parameter structure, side effects, return shape. It is front-loaded with the core action. Slightly long, but justified by the multiplicity of important details.

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?

Given no output schema and sparse annotations, the description covers all necessary context: purpose, parameters, side effects, return shape with nested fields, and error handling. It is fully self-contained for an agent to invoke correctly.

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?

With 0% schema description coverage, the description fully compensates by explaining the `items` array shape, the exact fields ({ transaction_id, category_id }), and where each ID comes from. This adds meaning beyond the raw schema.

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?

The description opens with a specific verb+resource: 'Corrects the category of one or more transactions (PATCH /transactions/:id)', immediately distinguishing it from sibling list/read tools. It states the operation clearly and unambiguously.

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?

It tells the agent when to use it ('to fix miscategorized transactions and improve categorization accuracy going forward') and references sibling tools for required IDs (openfinance_list_transactions, openfinance_list_categories). It doesn't explicitly mention when not to use it, but the context is clear.

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