get_cost_unit

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

The annotations already declare readOnlyHint=true and destructiveHint=false, so the read-only nature is clear. The description confirms 'Returns data' but adds no new behavioral details (e.g., no mention of error handling, rate limits, or response format). With annotations carrying the transparency burden, a score of 3 is appropriate.

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 one short sentence with no wasted words. While very concise, it could optionally include a hint like 'all fields of the cost unit' to improve completeness without adding bulk. For a simple tool, this is efficient.

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 the low complexity (1 required parameter, no output schema, no nested objects), the minimal description is borderline adequate. However, it does not hint at the structure of returned data, which might be expected since there is no output schema. An added phrase like 'including all fields' would improve completeness.

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% for the single parameter 'cost_unit_id', which already explains it as 'cost unit ID'. The description adds no additional meaning beyond the schema, so the baseline score of 3 applies.

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 verb 'Returns' and the resource 'specified cost unit', making the action unambiguous. It effectively distinguishes the tool from siblings like 'list_cost_units' (which returns multiple) and 'create_cost_unit'/'update_cost_unit' (which modify).

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 is provided on when to use this tool versus alternatives such as 'list_cost_units' or 'get_cost_unit' (if multiple get-like tools existed). The description does not mention context, prerequisites, or exclusions, leaving the agent to infer from the name alone.

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