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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description still adds genuine value by disclosing result structure the agent could not otherwise know – dose rows carry an origin label (clinical study, guide, community-reported, regulatory) plus sources and page links, which tells the agent how much to trust the data.

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?

Two dense sentences with zero filler. The one-peptide scope is front-loaded, and the provenance note about dose rows follows immediately where it is useful.

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 describing returns, and it does so well by listing the content areas and the provenance metadata attached to each dose row. It stops short of explaining pagination or whether the response is section-grouped, which a caller assembling a prompt would want.

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%, so both the peptide identifier and the sections enum are fully documented in structured form, making 3 the baseline. The description echoes the section names (reconstitution, side effects, storage, stacking, community) which reinforces the enum but adds no syntax or default behavior beyond it.

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 specific verb-resource pairing ("look up a peptide") and enumerates exactly what content comes back: dosing, reconstitution, side effects, storage, half-life, FDA status, stacks, community reports. The phrase "for questions about one peptide" implicitly separates it from peptide_compare, but it never names the sibling directly, so the boundary is inferred rather than stated.

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?

"For questions about one peptide" gives a usable trigger condition and quietly contrasts with the multi-peptide siblings. However, there is no explicit guidance on when to reach for peptide_search first, or when peptide_compare is the better route, leaving the agent to guess at the discovery-vs-retrieval boundary.

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