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

Beyond the readOnly/idempotent/openWorld annotations, the description discloses that it is pure arithmetic with no I/O, no external calls, no auth, and no rate limits, that results are rounded to 2 decimals, and that an unknown method or missing method-required parameter returns an error rather than a value. This is substantive behavioral context the annotations do not carry.

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?

It is a dense block rather than short, but the most decision-relevant content (method selects technique, sibling routing) is front-loaded and nearly every sentence earns its place by carrying method routing, unit conventions, error behavior, or return shape. Slightly heavy for a single paragraph, but not padded.

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 an 8-parameter, method-switched tool with an output schema, the description supplies the method-to-parameter mapping, unit conventions, error semantics, and side-effect profile, while leaving return-value detail to the output schema. Nothing an agent needs to invoke it correctly is 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 coverage is 100%, so the baseline is 3, but the description adds real meaning: it maps which parameters each method requires (black_scholes/binomial need underlying+strike+risk_free_rate+volatility+time_to_maturity, binomial adds steps, scenario_analysis needs scenarios), states that only method is required and the rest are method-dependent and should be omitted when unused, and clarifies that rate/decimal inputs are fractions and probability/weight lists sum to 1.

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 ('Advanced techniques: Black-Scholes call value, binomial-tree option value, and scenario analysis') and explains that 'Method selects the technique'. It explicitly differentiates itself from siblings valuation_probability and valuation_time_value, so an agent can route 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?

Gives explicit when-to-use and when-not-to-use rules: use valuation_probability with 'probability_weighted' for a quick expected value over arbitrary outcome lists, use scenario_analysis here for named bull/base/bear tables, and 'Not for plain discounted cash flow — for that use valuation_time_value'. Alternatives are named with the condition that selects them.

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