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

Annotations already cover read-only, idempotent, non-destructive, and closed-world, so the safety profile is settled. The description adds genuinely new behavior: results are ranked by how generous the free option is, and each result carries what's free, limits, the catch, how to start, and a last-checked date — details an agent cannot get from annotations.

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?

Three sentences, front-loaded with the purpose before the return-value detail, with no filler. The return-contents sentence is dense but every clause describes a distinct attribute an agent would act on.

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 no output schema, the description carries the burden of return values and does so thoroughly, including the ranking criterion and the per-tool fields. A ranked lookup with a fully documented schema and safe annotations needs little else; only sibling routing is left unaddressed.

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 query, limit, and no_signup are already documented in structured data. The description adds only illustrative query phrasings and says nothing about limit or no_signup that would extend the schema, so the baseline of 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 verb and resource ('Find free AI tools for a task or need') and anchors it with three realistic query examples, so the agent knows exactly what it searches over. It does not explicitly differentiate itself from the sibling find_free_alternatives, which overlaps on the 'free alternative to Canva' case.

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 example queries imply the right kind of input (a job, need, or named tool) and thereby hint at when this tool applies. However, there is no explicit when-not-to-use guidance and no routing to check_free_plan, compare_free_plans, or find_free_alternatives, leaving sibling selection to inference.

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