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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description need not restate safety. It adds useful context about the 'verified' nature of offers and the fact that it 'returns slim rows,' but does not disclose limitations like pagination or sorting. Given annotation coverage, a 3 is appropriate—the description adds some value beyond annotations but not extensive behavioral detail.

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?

Three sentences, no redundant phrasing. The purpose is front-loaded, the filter list is compact and informative, and the sibling redirect is placed at the end. Every sentence 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?

The description covers the tool's purpose, available filters, output format ('slim rows'), and directs to get_birthday_freebie for full terms. With no output schema and no required parameters, this is sufficient for an agent to call it correctly. It omits details like pagination or default ordering, but these are minor for a search 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 only 33%, but the description compensates by explaining every filter: 'actually_free (no purchase and no prior spend required)', 'kids (child-eligible)', 'no_signup', 'category (e.g. Restaurant, Beauty)', and 'name fragment' (which maps to the query parameter). This adds meaning beyond the bare types and examples, though the limit parameter is only covered by its own schema description.

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 'Browse verified birthday offers from US brands,' which specifies a clear verb, resource, and geographic scope. It distinguishes itself from sibling tools like search_deals by focusing on birthday-specific, verified offers and mentioning filters that are unique to this domain.

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 explicitly lists the search filters (actually_free, kids, no_signup, category, name fragment), giving the agent precise options for refining queries. It also states 'use get_birthday_freebie for the full terms of one brand,' clearly routing between this list-style tool and the detail tool.

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