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

Annotations already cover the read-only/idempotent/non-destructive profile, and the description adds real value on top: units convention (GBP, percent per year) and the firm rule that the State Pension forecast is user-supplied and never inferred. The claim 'All fields are required' is slightly inaccurate since include_projection defaults to false, but that is a minor imprecision rather than a contradiction of the annotations.

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?

Two sentences, front-loaded with the outputs the tool produces and followed by the input contract. Slight redundancy with schema unit descriptions, but nothing is wasted.

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?

With 15 parameters and no output schema, the description correctly takes on the job of naming the return values, including the compact-summary vs annual-rows behavior implied by include_projection. Gaps remain around edge behavior (e.g. what happens when the pot depletes before State Pension age), but the essential contract is covered.

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 100%, so every parameter is already documented in the schema; the description only restates the unit convention. It reinforces the statePension parameter's non-inferred nature but says nothing about interactions the schema cannot convey, such as how takeTaxFreeCash and remainingAllowance combine or what monthlyWithdrawal is gross of tax-wise.

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?

Specific verb and resource (project UK pension drawdown month by month) plus an enumeration of the outputs — pot after tax-free cash, first-year net income after tax, age the pot runs out, final balance. The 'UK' scope and the drawdown-specific outputs distinguish it from calculate_australia_super and calculate_retirement_income_gap without naming them, though no sibling is explicitly referenced.

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?

No guidance on when to choose this over calculate_australia_super or calculate_retirement_income_gap, and no exclusions or prerequisites stated. 'All fields are required' is an invocation constraint, not a statement of when the tool applies.

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