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

With no annotations, the description carries the behavioral burden and does provide useful context: it returns a Stripe Checkout URL, costs £0.49, is limited to England and Wales, and has 'Soft-Offer outbound is OFF'. However, it omits authentication needs, side effects, payment lifecycle, and error conditions.

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 short and front-loaded: paid pack, return value and price, geographic scope, and an operational flag. The final sentence is cryptic but does not make the definition verbose.

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 no annotations, no output schema, and 0% schema description coverage, the definition leaves important gaps. It explains the checkout URL and price but not the size parameter, usage routing, or key behavioral prerequisites for a paid tool.

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 0%, so the description must explain the two parameters. It gives geographic context for postcode but does not define its format, and it does not mention the size parameter at all.

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 states a specific paid pack for Domestic Energy Performance Certificates by postcode in England and Wales, and says it returns a Stripe Checkout URL at £0.49. That is clear enough to identify the tool's action and resource, but it does not explicitly distinguish it from siblings such as epc_discover or redeem_pack.

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?

There is no explicit guidance on when to use this tool versus epc_discover or redeem_pack. 'Paid pack' implies a purchase flow, but the description does not state prerequisites, alternatives, or when not to use it.

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