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

Annotations already declare this read-only, idempotent, non-destructive, so the safety profile is covered. The description still adds real behavioral content: it discloses the return payload (brands, one-line reasons, delivery mechanics, margin band, sign-up link) and a conditional rule — public store prices appear only when the market is a single country, not a region.

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?

A single dense paragraph that front-loads the action and the deliverable, then handles parameter meaning in the same breath. The only minor waste is restating the enum values after already defining them, but it reads as a compact reference 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?

With only three parameters, no output schema, and full schema coverage, the description covers everything needed to call it correctly, including the meaning of the market formats and the conditional price behavior. It stops short of stating what happens for unrecognized markets or regions, which would complete the picture.

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%, so the baseline is 3, and the description earns more by defining each programme_type value (card = credit/debit card benefits, loyalty = points redemption, telco = bundles and add-ons) beyond the bare enum, and by giving an illustrative audience_note example beyond the schema's example.

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?

Names a specific verb and resource ('Recommend 3 to 6 subscription brands for a business's programme in a market') and even enumerates the payload the agent will receive. It never contrasts itself with siblings like search_catalogue, so the agent must infer when to shortlist versus browse.

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?

Usage is implied by the phrase 'for a business's programme' plus the enumerated programme types, which signal a pre-sales/scoping scenario. There is no explicit when-to-use or when-not-to-use guidance and no pointer to the obvious alternative (search_catalogue) for plain catalogue lookups.

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