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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description supplements this by disclosing the return shape ('programmes with who qualifies and how to apply') and the geographic scoping of results via state/country. It does not discuss rate limits or failure cases, but the bar is lower with full annotation coverage.

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?

Front-loads the one-line purpose, then spends the rest on intent examples followed by a short return-value clause. The query list is long but each phrase maps to a real routing case (US vs UK, energy vs internet, provider-specific), so it earns its space rather than padding.

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 definition covers purpose, triggering intents, the geography mechanics and a summary of what comes back. Nothing an agent needs to invoke it correctly is missing; only the absence of explicit sibling/alternative guidance keeps it from being fully 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 100% and the schema already explains bill types, the state-to-country interaction, and the GB/UK scheme variants in detail. The description adds no parameter syntax or format information beyond that, so baseline 3 is appropriate here.

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 resource (official help programmes for a bill) and what it returns (programmes with eligibility and how to apply). The included user-phrased queries ('is there a broadband social tariff?', 'help with my energy bill in the UK') make it unmistakably distinct from get_bill_script and get_call_reminder, which handle talking points and reminders respectively.

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?

Gives rich when-to-use context via seven example questions spanning internet, energy, low-income broadband and provider-specific plan lookups. However, it never names a sibling tool or states when NOT to use this tool, so the alternatives remain implicit rather than explicit.

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