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

With no annotations, the description carries the burden and does disclose cost (6 credits, 'broad-scan premium') and a candid accuracy limitation (its heuristic logS is ~10× less accurate than covasolve_predict). It does not disclose auth requirements or any rate/input-size limits, but the cost and self-limiting accuracy disclosure is well beyond structured fields.

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 capability and size of the scan, then uses a tight bulleted exclusion list and a one-line cost note. Every sentence earns its place — the examples, the routing rules, and the price comparison all affect tool selection.

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?

An output schema exists, so return values need not be described, and the description fully covers selection, alternatives, and cost. The remaining gap is parameter-level guidance for the undocumented smiles/api_key inputs, which keeps it short of complete.

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% — neither 'smiles' nor 'api_key' has any schema documentation, so the description must compensate and it does not. It never explains the SMILES input format, whether salts/stereochemistry are accepted, or how api_key is obtained, leaving both parameters effectively 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+resource ('Broad physicochemical scan') and quantifies scope ('80+ properties in one call') with concrete examples (logP, TPSA, H-bond donors/acceptors, druglikeness flags). It explicitly distinguishes itself from siblings like covasolve_predict and covachem_druglikeness, so an agent can route without opening any 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 an explicit when-to-use rule ('general overview of a molecule') and a structured when-NOT-to-use list naming four alternatives with the exact condition that selects each (solubility→covasolve_predict, druglikeness→covachem_druglikeness, pKa→covachem_pka, ADME→covachem_adme). 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.