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

Annotations already declare readOnly, idempotent, non-destructive, closed-world. The description adds valuable non-obvious behavior: results are 'ranked' and 'verified', and closed offers are excluded unless filters.include_closed is true. It stops short of describing pagination or how ranking is computed.

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 question the tool answers, then examples, then the result field list, then the closed-offer caveat. Every sentence earns its place, though the long comma-separated field list is slightly dense.

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?

There is no output schema, so enumerating returned fields (credit_value, eligibility, how_to_claim, claim_url, source_url, source_snippet, last_verified) is genuinely necessary and well done. Combined with the exclusion rule and example needs, an agent has enough to call it correctly; only ranking/pagination details are 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% (both need and the nested filters are documented with examples and slugs), so the schema carries the parameter semantics. The description echoes only the include_closed default behavior and adds no new syntax or meaning 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 opens with a concrete verb+resource ('Answer what free credits / free tier / startup program can I get for X') and scopes the intent to ranked, verified offers matching a free-form need. It is clearly a natural-language search tool, distinguishable in spirit from siblings like get_offer or list_packs, though it never names those siblings explicitly.

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?

Three vivid example queries ('free speech to text credits', 'GPU for a bootstrapped startup', 'student LLM API credits') show how to phrase a need, which is real usage guidance. However, there is no statement of when to prefer this tool over get_offer/early_offers/recently_changed, and no when-not guidance.

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