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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine domain behavior beyond that: it defines where evidence_level and registry_level each come from and explicitly warns that a trial, phase or approval never raises evidence_level and that registry_level "says nothing about results" — exactly the trap an agent would fall into. It stops short of describing result shaping (view/compact behavior) or ordering semantics, which keeps it off a 5.

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?

Front-loaded with purpose, then alternatives, then field semantics; no filler sentences. It is slightly redundant in re-explaining evidence_level and registry_level after the parameters, but each sentence still carries routing or disambiguation value.

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?

The tool has 10 optional parameters, an output schema and full annotation coverage, so the description needn't document returns or safety. It covers purpose, routing and the one conceptually subtle part of the filter surface, leaving nothing an agent needs in order to call it correctly.

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 every one of the 10 parameters, including the enum values and the evidence/registry disambiguation, is already spelled out in the schema, so the description is largely restating it. It does usefully surface the evidence_level vs registry_level distinction at the top level, but adds no syntax, defaults or interaction rules the schema lacks — baseline 3.

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 opening sentence gives a specific verb and resource ("Return peptides with identity and evidence counts") and the rest names the two siblings it must be told apart from: resolve_peptide for a single unclear name and get_peptide_brief for a single summary. An agent can route correctly 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?

It states the browse/filter use case and enumerates the filter axes (text, category, kind, evidence level, registry level, curated launch list), then gives explicit exclusion routing to two named alternatives. This is the when/when-not/alternative pattern at full strength.

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