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

Beyond annotations (readOnlyHint=false, destructiveHint=false), the description discloses important side effects: it overrides Pluggy's automatic categorization and automatically creates a Category Rule affecting future transactions. It also explains batch error handling (per-item errors do not fail the batch). This is rich behavioral context that annotations alone do not convey.

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 efficiently structured: it opens with the core action, then parameter construction, then the behavioral nuance, then the use case, and finally the return shape. Every sentence adds necessary information, and the length is justified by the tool's complexity (batch behavior, rule creation, return shape).

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, the description provides the return shape explicitly, including the structure of `results` and `errors`. It also covers the side-effect of Category Rule creation and the source of parameter values, making it fully self-contained for an agent to invoke the tool 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?

Schema coverage is 0%, so the description carries the full burden for parameter explanation. It clarifies that `items` is an array of objects, and explains the provenance of `transaction_id` and `category_id` from specific sibling tools. This exceeds the schema's minimal type definitions, making parameter usage unambiguous.

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 begins with a specific verb+resource: "Corrects the category of one or more transactions (PATCH /transactions/:id)". This clearly states what the tool does and distinguishes it from sibling list/category tools. It also mentions batch capability, which further disambiguates.

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 description explicitly states when to use it: "use this to fix miscategorized transactions and improve categorization accuracy going forward." It also tells the agent where to obtain the required IDs from openfinance_list_transactions and openfinance_list_categories, effectively providing usage context. It does not name a direct alternative, but none exists among siblings for updating categories.

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