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

With no annotations, the description carries the full burden. It does disclose meaningful behavior: the scoring dimensions (efficacy, GC, thermodynamic asymmetry, off-target risk) and the 19-mer windowing approach. However, it never states this is a pure computation with no side effects, nor that an api_key credential is required, leaving safety/operational context thin.

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-loads the purpose in the first sentence and organizes parameters and returns compactly with no filler. The explicit Returns block is somewhat redundant since an output schema already exists, costing a small amount of space.

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 two-parameter tool, the description covers what it does, how it scores, the key input constraint, and the return shape. The only meaningful gap is the undocumented api_key parameter and absence of any usage routing context.

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 0%, so the description must compensate. It explains target_sequence well, adding the key constraint of minimum 21 nt and clarifying it is DNA even though the input is mRNA-derived. It says nothing about the api_key parameter, leaving one of two params undocumented.

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 (Design) and resource (siRNA candidates against a target mRNA), and names the exact methodology (Reynolds 2004 rules) plus the scored criteria. An agent can distinguish this from sibling design/analysis tools like covabasic_reynolds or covabio_mrna 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?

Usage is only implied: an agent infers this is the tool for designing siRNA from an mRNA sequence. There is no explicit when-to-use/when-not guidance, no mention of prerequisites, and no routing to alternatives among the many covabio/covabasic siblings.

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