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

Adds substantial context beyond the annotations: the list is polled once a day, the watchKey is returned only once and must be preserved, existing recalls are treated as already-known, webhookUrl is an optional https push channel, and no email/name/contact detail is stored. These are non-obvious operational and privacy facts an agent could not infer from idempotentHint/destructiveHint alone.

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?

Dense and front-loaded: purpose first, then the watchKey lifecycle, then the optional webhook and privacy caveat. Every sentence carries information, though the mode sentence partially overlaps the schema's parameter descriptions.

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?

An output schema exists, so return-value detail is not required, and the description covers creation, reading, updating, cadence, and key persistence. It leaves unaddressed edge cases such as invalid/expired watchKeys or how many watch lists a caller may hold.

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 baseline is 3, but the description adds real meaning: the mode semantics of omitting vs. supplying watchKey, the 1–10 product bound, and that products replace (not append to) the existing list. The webhook only receives JSON once a day, which extends the schema's terse 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?

States a specific verb+resource ('start a watch list of 1 to 10 product types and hear about new recalls') with geographic scope, and the dual-mode behavior (create vs. read vs. update) is explicit. It is clearly distinguishable from siblings like match_recalls (one-off lookup) and stop_watching_recalls (teardown).

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 concrete mode selection: 'Pass watchKey alone to read new recalls, or with products to change the list.' Cadence ('checked once a day') and the known-recall cutoff ('Recalls that exist today count as known') tell the agent what to expect, but no sibling alternative is named for one-time lookups.

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