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

Annotations already declare readOnly/idempotent/non-destructive, and the description still adds substantial behavioral context: retired catalog products are excluded, price/retailer/product_url come from scraped listings and may be missing or stale, and unresolved inputs return null data with a next_step. This is exactly the value-add beyond structured fields.

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-loads the core purpose then moves into field semantics; dense but essentially every sentence carries needed information given there is no output schema. Slightly run-on with multiple clauses packed into single sentences, but not padded.

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?

No output schema exists, so the description takes on the burden of explaining the returned fields (proofmark_100, proofmark_status states, match_basis, price/retailer staleness) and the error path, and it does so thoroughly for a 2-parameter tool.

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 coverage is 100% (baseline 3), and the description still extends the schema by clarifying that 'supplement' accepts either a plain name or an Aviado canonical_id, which the schema only calls 'Supplement name'. That extra accepted-input semantics justifies a 4.

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?

Opens with a specific verb+resource ('Highest-quality brands for a supplement'), states the dedup rule (one product per brand, its best) and the ranking basis (ProofMark). An agent can distinguish this from search_supplements or get_supplement_info without opening any schema.

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?

Explains when to prefer this and how to feed it ('supplement may be a name or an Aviado canonical_id (from search_supplements or a candidates list)') and gives a conditional workflow ('Check status first: needs_confirmation / no_match means the input did not resolve... next_step says how to retry'). It does not explicitly name a competing sibling for the same task, so no explicit when-not.

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