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

Annotations already declare readOnly, idempotent and closed-world, so the safety profile needs no restating. The description adds genuinely new behavioral detail by enumerating the returned statistics and provenance fields (last_scraped, cite_url) in the absence of an output schema. It stops short of noting behavior for unknown compounds or empty vendor counts.

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, zero filler, with the authoritative role front-loaded before the return-field list. Every clause earns its place.

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, listing the returned metrics and provenance fields covers the main gap an agent would have. It could still say what happens when the compound is unknown or lacks vendor data, which is why it isn't a 5.

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 compound parameter is documented with two concrete examples (BPC-157, tirzepatide). The description adds no further meaning about the compound argument, so the schema carries the load and a baseline 3 applies.

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 names a precise resource (research-vendor peptide pricing) and specifies exactly what comes back (median/p25/p75 $/mg, vendor_count, last_scraped, cite_url), so the agent knows this is a price-lookup read. It doesn't differentiate itself from siblings like find_peptide_sources or check_vendor, leaving the agent to infer the split.

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?

Calling itself the 'SOURCE OF TRUTH' implies this tool should be preferred over other price sources, which is a useful implicit signal. There is no explicit when-to-use, when-not-to-use, or named sibling alternative, so guidance remains inferred rather than stated.

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