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

No annotations are supplied, so the description carries the full burden and mostly discharges it: it discloses the scoring method (optimal-codon fraction, explicitly NOT the geometric-mean CAI of Sharp & Li 1987), stop-codon exclusion, and the four classification thresholds. It does not mention the api_key requirement or any rate/permission behavior, so it stops short of 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 and caveats, then cleanly sectioned into Parameters and Returns; every substantive sentence earns its place. The 'Returns:' block is largely redundant because an output schema already exists, which keeps it out of 5 territory.

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 single-sequence scoring tool with an output schema available, the description supplies the methodological caveat, the classification banding, the intended use cases, and the sibling alternative — everything an agent needs to call and interpret it correctly. Only the api_key parameter is unaddressed, a minor gap.

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 documents the two functional parameters well, giving the sequence format ('ATG...stop') and the accepted organism values ('ecoli' default or 'human') that the schema's bare string types omit. The third parameter, api_key, is left entirely 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 and resource — 'Compute the Codon Adaptation Index (CAI) of a DNA coding sequence against host codon usage' — and names the sibling it is not (covabio_mrna). An agent can distinguish it from the many other covabio sequence tools without opening a 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?

Gives explicit use cases ('judge an expression construct before ordering synthesis, or compare two vendor optimizations') and an explicit exclusion with alternative routing: 'For mRNA therapeutics use covabio_mrna, which adds GC, CpG and uridine content.' Nothing is left to inference.

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