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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds that output includes descriptions, counts, profiles and links, but discloses nothing about auth, rate limits, or caching, so it contributes only modest behavioral context beyond the 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?

Two sentences, both earning their place: the first front-loads what is listed and its payload, the second gives the follow-on action. No filler, no restating of the title.

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 an output schema present, the description need not detail return shapes, yet it still summarizes the contents and cross-references the sibling that consumes category ids. Combined with full annotations and a zero-parameter schema, nothing needed to invoke it correctly is 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?

The tool takes zero parameters, which is the baseline-4 case: there is nothing for the description to disambiguate in the schema. The description correctly implies a parameterless, retrieve-everything call and even explains where the returned category id is consumed (search_peptides), which is useful parameter-adjacent context.

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 gives a specific verb (List) and resource (Peptide Library research categories) and enumerates exactly what each entry contains: description, profile count, profiles, and links. It also differentiates from the discovery flow by pointing at search_peptides for filtered lookups, so an agent can place it against siblings like get_peptide_details.

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?

It states a concrete downstream use — "Use a category id with search_peptides to filter" — which tells the agent why and when to call this before searching. It stops short of explicitly naming when NOT to use it or which sibling to prefer for pure enumeration needs, so it is clear context rather than full routing.

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