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

With no annotations provided, the description carries the full burden. It does disclose useful output traits: monthly line items, credits earned or missed, and gotchas. However, it does not state whether this is a read-only operation, what inputs are validated, or what happens when the plan cannot be found, leaving the behavioral picture incomplete.

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 two sentences and roughly 25 words. The output content and scope are front-loaded, and the second sentence directly addresses how to identify the plan. Every sentence contributes without repetition or filler.

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 tool with three parameters, no annotations, and no output schema, this description gives a reasonable preview of the return content but leaves gaps: monthly_kwh is optional but not explained, zip format is unspecified, and no guidance is given about required territory checks or sibling-tool routing. It is adequate but not complete.

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 only 33%, so the description should compensate. It adds high-level meaning by linking 'zip and usage' to the matching parameters and clarifies that the plan can be identified by id, slug, or name, though the latter is already in the schema. It omits format details for zip and units for monthly_kwh, so the compensation is only partial.

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 identifies the tool as producing a receipt/breakdown for one plan at a given zip and usage, which distinguishes it from sibling tools like compare_plans. However, it lacks a direct verb such as 'explains' or 'returns', relying on the noun phrase 'The receipt for one plan' to convey the action.

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?

The phrase 'one plan' implies this is for analyzing a single plan rather than comparing plans, so the context is somewhat clear. But there is no explicit guidance about when to use this tool versus check_territory, compare_plans, or compare_this_house, nor any when-not-to-use conditions.

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