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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description does not need to repeat safety behavior. It adds useful behavioral context by stating the return fields (calculator_id, name, description, use_when, required inputs) and clarifying that no calculation is performed.

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 compact and front-loaded, with the core action in the first sentence. It includes only necessary context: filtering, return contents, and tool selection guidance. The category enum list is slightly redundant with the schema but does not bloat the description.

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 read-only list tool with one optional parameter and no output schema, the description fully covers what the tool returns and when to use it. The lack of pagination or error details is not significant given the tool's low complexity.

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 description coverage is 100% and the only parameter is already well described with an enum. The description adds the 'optionally filtered' semantics and lists the category values, but this is largely redundant with the schema, so the baseline of 3 is appropriate.

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 states a specific verb and resource ('List all calculators') and clarifies it is a browsing tool, not an execution tool, explicitly saying 'Does not perform calculations.' It also distinguishes itself from sibling search_calculators by mentioning alternative lookup behavior.

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 gives explicit guidance: 'Use it to browse a whole category; use search_calculators for keyword lookup.' This directly tells the agent when to choose this tool over an available sibling, leaving little to inference.

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