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

Annotations already declare readOnly, idempotent, and non-destructive behavior, and the description adds genuinely new context: one result per country of operation, null-vs-0 semantics for minimum_payout, the bonus being credited only via its specific URL, and the requirement to render that URL as a clickable link. No contradiction with annotations; it goes well beyond them.

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 core purpose is front-loaded and nearly every sentence earns its place, including field semantics and the presentation constraint. However, the sentence 'Use these to answer questions about a portal's sign-up bonus, payout threshold, payment schedule and payment options' largely restates the earlier when-to-use sentence, a minor redundancy in an otherwise tight description.

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 2-parameter search tool with 100% schema coverage, full annotations (readOnly, idempotent, non-destructive), and an output schema, the description covers result multiplicity, field-level semantics, and how to present bonuses. Nothing an agent needs to call it correctly or interpret its results is missing.

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 both parameters already carry rich descriptions (case-insensitive word-boundary matching, best-match ordering, country-code format, 'gb' not 'uk', when to pass or omit country_code). The description adds portal examples and result-field semantics but no parameter meaning beyond the schema, so the high-coverage baseline of 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?

The description opens with a specific verb-resource pair: 'Searches cashback portals by name' with concrete examples (Rakuten, TopCashback, Honey), and states the exact output shape: 'returns each match with its payout terms, one entry per country.' It differentiates from siblings by scope (by name vs. by id vs. list-all) and explicitly contrasts with get_cashback_rates_by_store_name.

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 explicit when-to-use conditions ('Use it when the user asks about a named portal: its sign-up bonus, minimum payout, how often it pays, or which payout methods it offers') and an explicit when-not-to-use with the named alternative ('For a store's cashback rate at that portal, call get_cashback_rates_by_store_name and read the "portal" field'). This fully routes the agent with no inference required.

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