STRING: Search proteins by amino acid sequence

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

No annotations are provided, so the description carries the full burden, and it does disclose the core behavior: results are the most similar STRING protein(s) for a given species, ranked by sequence similarity, and input may be one or many FASTA records. It stops short of stating failure behavior (no match found), confidence/threshold semantics, or whether a fuzzy best-hit match is returned blindly, which for a similarity-lookup tool would be the most valuable remaining disclosure.

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/tight bullets, front-loaded with the purpose and then the routing rule. No filler, and the most decision-relevant information (when to use it) comes last where it is easy to scan.

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?

With an output schema present, the description need not explain return values, and the schema covers both parameters, so the description is close to sufficient. The only gap is that a similarity-based matcher can return an approximate hit, and nothing here tells the agent how to interpret or validate that result.

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%, so both 'species' and 'sequences' are already fully documented in the schema. The description restates the FASTA/multi-sequence capability but adds no syntax, default, or format detail beyond what the schema provides; 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?

States a specific verb (searches) plus the resource (STRING database) and the discriminating input modality (amino acid sequences) that separates it from identifier-based siblings. It also names the specific alternative, string_resolve_proteins, so an agent can route correctly without opening schemas.

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?

Explicit routing rule: 'Use this when the protein identifier is unknown or unresolvable by string_resolve_proteins.' This gives both the condition that selects this tool and the alternative it replaces, which is exactly what is needed among 17 sibling tools.

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