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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so safety is covered. The description adds the default months value and the output fields, but not deeper behavior like what happens when both identifiers are provided or the history limit.

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?

Well organized with purpose, output summary, args, and returns. Slight redundancy between 'Shows utilization percentage, over/under status' and the Returns section, but otherwise no wasted words.

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?

Adequate for a read-only query tool: it documents all parameters and return values. Missing edge cases like providing both identifiers, neither identifier, or invalid month counts, but an agent can likely call it correctly with the given information.

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. It clearly explains each parameter, especially the OR relationship between budget_id and category_name, and the default value of months, adding meaning beyond the 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?

States the verb 'get', the resource 'budget performance', and the scope 'over time (actual vs budget per month)', which clearly distinguishes it from budget streaks or category trend tools. It doesn't explicitly name sibling tools, but the budget-vs-actual focus is specific enough.

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?

No guidance on when to use this versus other analytics tools such as get_budget_streaks or get_category_trend. The 'provide this OR category_name' instruction is parameter usage, not tool-selection context.

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