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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered; the description adds that results are programmes with eligibility criteria and application instructions. It says nothing about coverage gaps, rate limits, or what happens when no programme matches, which caps it below 5.

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?

Purpose is front-loaded in the first two sentences, then a block of example queries follows. The examples are repetitive in structure but each maps to a distinct intent, so they mostly earn their place; the list is slightly longer than strictly necessary.

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 three-parameter read-only lookup with no output schema, the description covers intent, input framing and the shape of the result (programmes, eligibility, how to apply). Annotations carry the safety profile and the schema carries parameter detail, leaving no blocking 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 description coverage is 100%, so the meaning of bill, state and country (including which states unlock energy discounts and the GB/UK behaviour) is fully documented in the schema itself. The description's examples align with those semantics but add no syntax or format detail beyond them, so baseline 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?

States a specific verb and resource (retrieve official help programmes for a bill) and reinforces it with concrete user-phrasing examples covering internet, broadband, energy and provider-specific cases. An agent can distinguish this from lowermybill_get_bill_script and lowermybill_get_call_reminder purely from the description.

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 example queries ('is there help paying my internet bill?', 'does Xfinity have a low-income plan?') give an agent clear routing signal for when this tool applies. It stops short of naming alternatives or stating when not to use it, so it is clear context without explicit exclusions.

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