set_cost_per_call

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

No annotations are provided, so the description carries the full burden. It discloses that setting this cost affects cache_stats output and mentions a default. However, it does not state whether the change is persistent, whether it overwrites previous values, or what happens if the instance doesn't exist. Given the simple nature of the tool, a 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?

Five sentences, each earning its place: purpose, usage context, default, examples, consequence, prerequisite. Front-loaded with the core action and immediately useful. No fluff.

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 (2 required params, no nested objects) and no output schema, the description covers the input well but omits what the tool returns (e.g., success confirmation). It implies success via 'After updating, cache_stats will show...' but does not state return value. For a simple setter, this is a minor gap.

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 100% (both parameters have descriptions). The description adds significant value beyond the schema: default cost value, mapping model names to example costs, and linking to list_instances for instance_id. This extra context justifies a score above the baseline of 3.

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 clearly states the verb 'Set' and resource 'assumed cost per avoided LLM API call' for a specific instance. It explains the purpose (accurate ROI savings in cache_stats) and provides concrete examples, distinguishing it from sibling tools like cache_set or cache_stats.

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 provides context for when to use: to set actual model cost for accurate numbers, with examples. Recommends using list_instances first to find instance_id. Does not explicitly state when NOT to use or compare to alternatives, but the narrow scope makes this less critical.

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