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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds value by stating that results are 'verified' and include 'check dates', implying a research/read operation and giving insight into output characteristics. It does not mention side effects, but as a search tool, none are expected. This goes beyond a bare function statement.

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?

The description is two sentences long, front-loaded with the primary action, and every phrase contributes meaning. It efficiently covers both purpose and usage without redundancy or filler.

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 adequately covers purpose, usage context, and return content ('verified allowances and check dates'). For a simple 3-parameter tool with no output schema, this is sufficient. It could slightly improve by explicitly stating the return format (e.g., a list of alternatives), but the current wording implies it.

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?

The input schema already provides descriptions for all three parameters (lang, tool, works_in_china), achieving 100% coverage. The description adds context for the 'tool' parameter by framing it as a tool whose free tier is insufficient, but it does not elaborate on the optional parameters or add new semantic details beyond the schema. 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?

The description clearly states the tool finds entirely free alternatives in the same category for a given tool, with verified allowances and check dates. This distinguishes it from sibling tools like check_free_tier_claim or compare_free_tiers, which focus on checking claims or comparing tiers rather than discovering substitutes.

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?

The description explicitly says when to use the tool: when a user's free tier is insufficient, cannot access a service from their region, or wants a no-cost substitute. This provides clear context and implicitly excludes situations where a paid tool is acceptable, distinguishing it from alternatives.

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