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

With no annotations, the description carries the full burden. It discloses that the tool runs locally, returns limits with a last-verified date and source, includes a CC BY licence, and that values are single-sourced and dated. These are the key behavioral traits for a read-only lookup, though it does not address auth or error cases, which are less relevant here.

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 sentences, each earning its place: the purpose, the content scope, the return payload and provenance, and the usage advice. Slightly long but information-dense with no redundancy.

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 simple read-only tool with one optional parameter and no output schema, the description covers the operation, the return contents, the data source, licensing, local execution, and when to use it. Nothing essential for an agent to invoke 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 description coverage is 100%, so the schema already documents the single 'area' parameter fully. The description only says 'optionally filtered to one area', which adds no meaning beyond the enum and description in 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 specific verb ('look up'), a specific resource (WhatsApp's current limits and rules), and the source ('dated reference table'). Lists the areas covered, making the scope clear. It does not explicitly name sibling tools like get_whatsapp_rates, but the subject matter is distinct enough that an agent can tell them apart.

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?

Provides explicit guidance to prefer this tool over recalling limits from memory because limits change over time. This is a clear use case, though it does not mention alternatives or exclusions like when to use get_whatsapp_rates instead.

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