set_budget

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

The annotation readOnlyHint: false already indicates a write operation. The description adds behavioral context by stating it 'Returns the updated budget details', which tells the agent what to expect. It also clarifies the month format and hints that categories should come from list_categories. There is no contradiction with annotations.

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 three sentences and front-loaded with the primary purpose. It is concise, but the second and third sentences largely repeat information already in the schema (month format, list_categories). Despite this redundancy, it remains appropriately sized and scannable.

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 simple 3-parameter write operation, the description is complete: it states the action, specifies the month format, points to list_categories for valid categories, and mentions the return value. The presence of an output schema reduces the need to detail return fields. It lacks error handling or side-effect notes, but these are not critical for this straightforward mutation.

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 input schema has 100% description coverage for all three parameters. The description repeats the month format and list_categories hint verbatim from the schema, adding no new meaning beyond what the schema already provides. Therefore, baseline 3 is appropriate; the description does not enhance parameter understanding.

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 clearly states the action: 'Set the budget amount for a category in a given month in Actual Budget.' The verb 'Set' and resource 'budget' are explicit, and this tool is distinct from sibling list/transaction tools. It also specifies the target (category, month, amount) which fully clarifies the scope.

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 provides clear context (when to use: for a given month and category) and a prerequisite (Use list_categories to get category names). It does not explicitly mention alternatives or when-not-to-use, but given the sibling tools are mostly list operations, this unique write operation is obviously the right choice for setting budgets. The month format requirement is also a useful guideline.

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