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

With no annotations, the description carries the full burden. It adds context about data verification ('Every verified entry carries its official source and check date') and cites a source, which is useful. However, it does not disclose potential behavior like rate limits, result pagination, or whether the directory is static or updated, though as a search tool it is inherently non-destructive.

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 three sentences, front-loaded with the core purpose, and each sentence adds value: purpose, filters, and data provenance/citation. No unnecessary words or repetition.

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?

Given no output schema, the description provides some return context by mentioning that each entry has source and check date, but it does not describe the full result structure or pagination. The 6 optional parameters are well-covered by the schema, and the search tool's behavior is adequately conveyed for a directory search.

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%, providing full parameter documentation, so the baseline is 3. The description adds a partial list of category values (missing a few like 'study', 'local', 'safety') and maps 'fully-free flag' and 'works-in-mainland-China flag' to the boolean parameters, but this is only marginal extra meaning beyond the schema.

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 'Search a verified directory of 218 AI tools with genuine free tiers', using a specific verb ('Search') and resource ('verified directory'). It also lists distinct filters (category, fully-free, works-in-mainland-China, keyword), distinguishing it from sibling tools like find_free_alternatives or check_free_tier_claim.

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 provides clear context for when to use the tool: searching for AI tools with free tiers, with filters matching the schema. However, it does not explicitly name alternatives or state when not to use it, such as saying 'for verifying a free tier claim, use check_free_tier_claim'.

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