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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that: the energy model (Turner 2004 nearest-neighbour parameters, kcal/mol) and cross-validation against ViennaRNA 2.7.2, plus the fact that it reports pairing rather than a score. It stops short of discussing performance or limits, hence a 4.

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, front-loaded with the core action, then rationale, then methodology. Every sentence carries information and none is filler, though the third sentence's tool-version detail is slightly dense.

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, return values need not be re-explained, and annotations cover safety. The description still supplies the scientific framing, the output content (paired bases), the energy model, and scaffold-selection context, leaving nothing essential for a correct invocation missing.

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 the schema already documents spacer, sg_rna, nuclease, and the _subject/_files references. The description adds only loose context (folding 'the spacer alone, and the whole sgRNA') that maps to the sg_rna flag, so the baseline 3 is appropriate.

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 (fold) and resource (a guide RNA / sgRNA on a published scaffold) and clarifies the deliverable: which spacer bases pair with the scaffold. The scope is narrow enough that an agent can tell it apart from the general-purpose fold_rna sibling without opening the 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?

The rationale (a spacer base-pairing into the scaffold physically disrupts Cas9 binding, causing a dead guide) implies when the tool is useful, but the description never explicitly states when to use it versus alternatives like fold_rna or the crispr scoring tools, nor any exclusions. Usage is implied rather than stated.

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