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

Goes well beyond the readOnly/idempotent/closed-world annotations: pure arithmetic, no I/O, no external calls, rounded to 2 decimals, no auth or rate limits, and explicit failure behavior (unknown method or missing method-required parameter returns an error instead of a value). The annotations cover the safety profile and the description adds the operational and failure semantics.

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?

Dense but well front-loaded: purpose, usage, per-method parameters, exclusion, units, return shape, error behavior. Most sentences earn their place, though the clause about "probability and weight lists are in [0,1] and sum to 1" refers to parameters that do not exist in this schema and reads as template carry-over.

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 10-parameter tool with one required enum, the description covers selection, conditional parameter applicability, units, return contents, and error conditions. With an output schema present it correctly does not over-explain return values, and 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 would be 3, but the description adds the method-to-parameter mapping (ppp needs spot_rate + inflation_foreign + inflation_domestic, etc.) that the schema does not express, plus unit conventions (fractions where 0.10 = 10%) and the rule that only method is required while the rest are conditional.

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?

Opens with a specific verb+resource+scope: cross-border adjustments covering PPP, country risk premium and international CAPM. It explicitly distinguishes itself from the sibling valuation_capm ("Not for the domestic cost of equity") and names two complementary siblings, so an agent can route correctly 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 explicit use conditions ("Use for cross-border cash flows and country risk"), pairings (valuation_capm, valuation_time_value), and a clear exclusion with the alternative named. The when/when-not/alternative triad is fully covered.

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