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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds the return payload shape and the '(free)' cost signal, which is genuinely useful behavioral context not present in structured fields, but it says nothing about rate limits, caching, or what happens when a slug/alias doesn't resolve.

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?

One short sentence plus a cost tag, front-loaded with the 'answer-first' framing and the payload contents — nothing redundant. It is slightly telegraphic and the '(free)' tag is left unexplained, but no sentence is wasted.

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?

For a single-parameter read-only lookup with no output schema, the description does the necessary job of describing the returned fields (takeaway, status, grade, citation count, URL). Combined with full schema coverage and clear read-only annotations, an agent has enough to call it correctly, though the absence of sibling routing leaves a small gap.

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% and the single slug parameter is already documented as 'Peptide slug or alias'. The description adds no information about slug format, alias resolution behavior, or failure modes, so the baseline 3 applies with the schema doing all the work.

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 enumerates what the summary contains (takeaway, status, evidence grade, citation count, URL) but never states the verb+resource the way the name does — it relies on 'get_peptide_summary' to convey that this returns a summary for a peptide slug. It hints at a distinction from heavier siblings like get_peptide or get_citations by being 'answer-first', but doesn't make that contrast explicit.

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?

There is no when-to-use guidance and no named alternative among the ten siblings; an agent must infer that this is the lightweight first-look tool versus get_peptide or get_citations. The parenthetical '(free)' is the only usage signal, implicitly suggesting it is cheaper than other lookups, but that is left unstated.

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