fire_number

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

The annotations already declare readOnlyHint=true, indicating this is a calculation tool without side effects. The description adds useful context about what the tool calculates (portfolio size and timeline) and mentions the classic 'Rule of 4%', but doesn't provide additional behavioral details like error conditions, performance characteristics, or data persistence. No contradiction with annotations 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 description is perfectly concise with just two sentences that efficiently explain both primary functions: calculating the FIRE number and estimating the timeline. Every word earns its place, and the information is front-loaded with no unnecessary elaboration.

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 purpose as a financial calculator with read-only behavior (annotations), comprehensive parameter documentation (100% schema coverage), and the existence of an output schema, the description provides complete context. It clearly explains what the tool does without needing to detail return values or behavioral nuances that are covered elsewhere.

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?

With 100% schema description coverage, all parameters are well-documented in the schema itself. The description mentions the core parameters (expenses, withdrawal rate, savings) but doesn't add significant semantic information beyond what's already in the schema descriptions. The baseline score of 3 is appropriate when the schema does the heavy lifting.

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 calculates the FIRE number (portfolio size needed) and timeline (years to reach FIRE). It specifies the verb 'calculate' and resource 'FIRE number and timeline', distinguishing it from sibling tools like compound_interest or mortgage_calculator which handle different financial calculations.

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 provides clear context for when to use this tool: for calculating financial independence metrics based on expenses, withdrawal rates, and savings. However, it doesn't explicitly state when NOT to use it or mention specific alternatives among the sibling tools, though the different tool names imply different use cases.

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