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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description correctly spends its words elsewhere: it discloses the fallback path when PepBank has no data (a PepBank link is returned) and imposes an operational requirement to surface the credit line with the answer. These are genuine behaviors not present in the annotations. Missing only peripheral details such as latency or rate limits.

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?

Three sentences, zero filler, and the payoff (what the brief contains) is front-loaded before the routing rule. Each sentence carries a distinct load: contents, selection rule, empty-result behavior.

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 read-only, single-parameter tool with no output schema, the description compensates by describing the return payload in concrete sections and by explaining the degenerate case (no PepBank data). An agent knows what it will get back and how to route around an empty result, which is the full job here.

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 fully documented in the schema with examples (BPC-157, tb-500), so the description need not restate it. The description only reinforces that the argument is a single named peptide ("one peptide"), adding no format or slug-resolution guidance beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 opens with a specific verb+resource ("Read the PepBank brief for one peptide") and enumerates exactly what the brief contains: aliases, evidence split by human/animal/lab, findings with citations, regulatory status, credit line. That scope statement distinguishes it cleanly from search_research, which the description explicitly names as the multi-study alternative.

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 an explicit positive trigger ("Use it when the user names one peptide") and an explicit negative/alternative case ("Use search_research for a question across many studies, such as an outcome or a body system"). Both the when and the when-not are stated with the condition that selects between them.

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