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

With no annotations provided, the description carries the burden of behavioral disclosure. It discloses the core calculation logic (investment grows to target by retirement) and hints at a gap awareness via 'Mind the gap.' However, it does not specify output format, how current savings are compared, edge-case handling (e.g., currentAge > retirementAge), or potential error messages. It is more than a tautology but lacks detailed behavioral context.

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 main sentence is concise, front-loaded, and informative. The second element 'Mind the gap' is short but vague, adding personality rather than clear technical value; it slightly detracts from clarity but does not make the description bloated. Overall, it is appropriately sized.

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?

Given the tool's complexity (5 required parameters, no output schema, no annotations), the description is incomplete. It explains the fundamental concept but does not cover expected return values, assumptions (beyond zero contributions), parameter relationships, or error conditions. An agent would struggle to anticipate the tool's full behavior from this description alone.

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%, so the description must compensate. It mentions 'FIRE target' and 'retirement' and 'invested today,' but does not directly define the five parameters (currentAge, currentSavings, targetFireNumber, retirementAge, realReturnPct). Some meanings can be inferred from parameter names, but the description adds minimal semantic value for the parameters themselves.

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?

The description clearly states the tool's purpose with a specific verb ('Find') and a specific resource ('your Coast FIRE number'), and defines the concept. It distinguishes itself from sibling tools by explicitly noting the 'zero further contributions' criterion, which sets it apart from general FIRE or compound interest calculators.

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?

The description implies when to use it (for Coast FIRE scenario with zero future contributions) but does not explicitly mention alternatives or exclusions. Sibling tools like fire_calculator exist, yet no direct comparison is made. The phrase 'zero further contributions' provides context, but it lacks an explicit 'use this when' or 'instead of' guidance.

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