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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered; the description goes well beyond that by disclosing the matching cascade (exact alias, normalized alias, trigram, edit distance), the normalization rules, the 2-error edit-distance cap restricted to featured peptides, and that trigram/edit-distance results are guesses. It also explains the ambiguous-status behavior, which is exactly the kind of outcome semantics an agent needs.

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?

Purpose and the sibling alternative are front-loaded, then matching details follow in a logical order. It is dense with short declarative sentences, though the normalization and edit-distance sentences could be tightened slightly without losing information.

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?

An output schema exists, so return values need not be described, and the description still covers the one non-obvious return case (ambiguous status yields candidates without a selection). For a single-parameter read tool, nothing an agent needs to call 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?

Schema coverage is 100% and the single parameter is already documented with an example, so the baseline is 3. The description adds real meaning beyond the schema by explaining what forms the 'name' accepts (alias, code, Greek-letter names, case/space/hyphen-insensitive) and how fuzzy input is tolerated.

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 and resource ('Return peptide IDs and name matches for a name, alias or code') and explicitly distinguishes itself from the sibling search_peptides, which it names. An agent can tell the two apart without opening either 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?

Gives explicit when-to-use guidance ('Use this before other calls when the name is unclear') and names the alternative with the condition that selects it ('Use search_peptides instead to browse or filter many peptides'). Both the positive and negative cases are covered.

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