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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds real behavioral context beyond that: exactly one method must be supplied with its declared inputs, there are no defaults, and invalid input returns an error envelope (code INVALID_ARGUMENT) rather than raising. It doesn't need to describe output because an output schema exists.

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?

The purpose, alternatives and error contract are front-loaded, and every sentence carries information. The method/input listing is dense but necessary since the schema defers it here; it is slightly run-on 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 a 6-method, 10-parameter calculation tool this is complete: method-to-input mapping, alternatives, and error behavior are all covered, and return values are handled by the output schema. Nothing an agent needs to call 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 field meanings are already documented, but the description adds cross-parameter semantics the schema cannot express: the exact input set required per method value, the exactly-one-method constraint, and that no defaults apply. That mapping meaningfully exceeds the per-field descriptions.

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 ('fair-value-adjustment engine', 'compute exit-price adjustments') and enumerates the adjustment types (credit, liquidity, control, marketability, blockage, hierarchy). It explicitly distinguishes itself from siblings calculate_market_multiple and calculate_credit_loss, so an agent can route correctly without opening another 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 ('move from an indicated value to the fair value recognised in the accounts') and names the alternatives with the condition that selects them (liquidity/marketability inputs of a listed instrument -> calculate_market_multiple; expected credit loss -> calculate_credit_loss). 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.