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

Goes well beyond the readOnlyHint/idempotentHint annotations by disclosing that answers are deterministic rule output (never invents prices or opening hours), that language detection is automatic, that authentication uses the connection API key, and that a missing key degrades to a public demo business. Those are non-obvious operational traits the annotations cannot convey.

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?

Front-loaded with the core purpose in the first sentence, then progressively adds constraints, auth, and return shape. Each sentence carries new information, though the single dense block packs many clauses and could be split for easier scanning.

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?

No output schema exists, and the description compensates by enumerating the returned JSON keys { intent, lang, matched, reply, next? }, which is exactly what the agent needs to interpret results. Together with auth, fallback, and routing behavior, nothing essential 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?

With a single parameter at 100% schema description coverage, the schema already documents the message field, its 1–2,000 char limit, and the 'don't rephrase or translate' rule. The description adds only the language-detection note (English/Chinese) plus the return shape, so the baseline 3 is appropriate.

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 ('Answer a customer's message') scoped to 'one small business using only that business's own FAQs and order records', which distinguishes it from the sibling booking/cancellation tools. The 'rule-based, not generated' clause further pinpoints what kind of answer is produced.

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?

Explicitly says 'Use it first for any customer message' and gives concrete branching rules: intent 'appointment' → call list_open_times next; matched is false or intent 'human_handoff' → tell the customer a person will follow up. This routes the agent to alternatives and defines the fallback path.

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