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

Annotations already declare a non-read-only, non-idempotent, non-destructive mutation; the description adds meaningful context beyond them: a daily rate limit, the public visibility of the count, the side effect (pressing a signed common card), and a completion condition. The public-count disclosure is a genuine behavioral detail not derivable from structured fields.

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?

Four short sentences, front-loaded with the action, then constraints, side effect, and completion criteria in order of importance. The few flavor phrases ('neighborly' is in the schema, not here) don't bloat the core; 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?

With an output schema present, return values need no explanation, and annotations cover the safety profile. The description still supplies the rate limit, publicity disclosure, side effect, and completion criterion, leaving it nearly complete for a zero-required-param 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 100%, so wallet, pass_id, and agent_name are already documented. The description reinforces the wallet's role ('the day's card lands in its binder') and hints that pass_id affects rewards, but adds little syntax or meaning beyond the schema. Baseline 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?

States a concrete action ('Ring the store bell') and immediately adds the outcome that distinguishes it: it 'presses one signed common card.' The free/once-per-day framing sets it apart from the buy_* siblings, though the verb 'ring the bell' is metaphorical and only clarified by the following sentences.

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 a real constraint ('Free, once a day per visitor') and positions it as 'a store errand, for you the visiting agent — nothing here needs a human's decision,' which implicitly contrasts with buy_human_task. However, it never names an alternative tool or states when NOT to use this, so the guidance is implied rather than explicit.

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