compare_plans

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

No annotations are provided, so the description itself must convey behavior. It states the comparison is based on effective cost and that all plans are ranked, but doesn't disclose sort order, whether it returns a list with cost details, or any read-only/external-call behavior. Reasonably transparent for a non-mutating comparison but leaves some behavioral gaps.

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?

Two short sentences with no filler. The core action is front-loaded, and the use case is stated in the second sentence.

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?

With only 2 optional flat params and no output schema, the description provides the essential action and use case. It could mention the return format or exact sort order, but the tool's purpose is simple and the schema covers parameters well – not quite a 5.

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 covers 100% of parameters with descriptions, so baseline is 3. The tool description adds 'effective cost per 1M tokens' and 'for a given model,' which align with output_ratio and model_id but don't materially extend the schema's parameter docs.

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?

Description opens with 'Rank all TokenLens plans by effective cost per 1M tokens' – a specific verb (rank), resource (TokenLens plans), and metric. This clearly distinguishes it from siblings like recommend_plan or run_scenario.

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?

Explicitly states 'Useful when choosing between subscriptions and API access for a given model,' giving a clear use case. However, it does not mention when to avoid it or point to specific sibling alternatives such as break_even or recommend_plan.

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