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

Annotations only declare it as a safe, idempotent, closed-world read. The description goes well beyond that by disclosing the data freshness window (checked within 3 days), the exact discount threshold, and the contents of each result including the lowest recorded price used to sanity-check the was-price. That is substantive behavioral context an agent could not infer from the annotations.

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?

Two sentences, zero filler, with the scope and qualification rule front-loaded before the result-field inventory. The enumeration of result fields is dense but each item is informative and earns its place.

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 six-parameter filtered search tool with no output schema, the description covers scope, eligibility criteria, freshness, result shape, and available filters. Nothing an agent needs in order to call it correctly 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 coverage is 100%, and every parameter (sort, brand, limit, query, category, min_percent_off) is documented with defaults and enums in the schema itself. The description only adds that filtering is available by keyword, category or brand, which restates rather than extends the schema — baseline 3 is correct.

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 names a specific resource (live markdowns on EDC products Drop Beacon tracks) and states the exact inclusion rule: in-stock items at least 10% below the seller's own compare-at price, verified within the last 3 days. That is far more precise than the title and lets an agent distinguish it from siblings like deal_check and find_offers.

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?

It gives clear context for when this tool is appropriate — you want current, verified discounts rather than general offers or upcoming drops — and notes the filter axes (keyword, category, brand). It never explicitly says when NOT to use it or names a sibling (e.g. deal_check for a single product) as the alternative, so it stops short of full routing guidance.

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