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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds useful behavioral context the annotations don't: the response contains numbered sources and a course link per peptide, which matters because there is no output schema.

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?

A single sentence that front-loads the operation, then the output shape, then concrete examples. No redundant or filler text.

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 one-parameter read tool with no output schema, the description does enough: it explains what is returned (summaries, numbered sources, course link) and when to reach for it. Minor gaps remain around invalid/unknown peptide handling and result ordering.

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% and already documents 'Two or three peptide ids or names' with minItems 2 / maxItems 3. The description's 'two or three peptides' merely restates the schema bounds and adds no format or resolution guidance (e.g. what happens with an unknown id). 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?

States a specific verb+resource ('put the research summaries of two or three peptides side by side') and clearly implies the singular sibling get_peptide_research is not the right call. An agent can tell this apart from list_peptides and get_peptide_research 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?

Concrete trigger examples ('BPC-157 vs TB-500', 'semaglutide vs tirzepatide') make the use case unambiguous. It doesn't explicitly state when not to use it or name the sibling to fall back on for single-peptide lookups, so it stops short of a 5.

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