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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, destructiveHint false. The description adds beyond that: what the record includes (sequence, annotations, cross-refs, etc.) and the effect of the format parameter. No contradiction.

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?

The description is concise, uses examples and a clear structure. It front-loads the purpose and lists return elements efficiently. Minor improvement: could break into separate lines for readability.

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?

Given that an output schema exists (not shown but referenced), the description is adequately complete: it covers the tool's primary use, parameters, and return content. It doesn't discuss error handling, but that's acceptable for a simple fetch tool.

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 description coverage is 100% (both parameters documented). The description adds value: it explains that format=fasta returns 'sequence only', and gives example accessions. This aids parameter usage beyond the schema.

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 clearly states it fetches a single UniProtKB entry by accession, with examples like 'P38398 for BRCA1_HUMAN'. It specifies return content (sequence, function annotations, GO terms, etc.) and distinguishes from search tools (siblings include 'search', 'entity_profile').

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?

The description tells when to use: when you have a known accession and want the full record or FASTA. It does not explicitly state when not to use, but the sibling context implies alternatives for searches. Adding explicit exclusions would improve.

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