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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds substantial behavioral context beyond that: the returned country tiers, FIRE numbers per tier, visa income-floor eligibility, local-currency income, SWR sensitivity, years-to-unlock behavior with savings/coast, and the important caveat that the statePension overlay is not subtracted from FIRE numbers. It also clearly labels the output as estimates and not financial advice.

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 one long, dense sentence, but it is front-loaded with the core analysis and then enumerates output details. The parentheticals and nested clauses are justified by the tool's complexity, though the single-sentence structure is slightly heavy.

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 an output schema present, the description need not enumerate every return field, but it still explains the output shape, tier logic, overlay semantics, and estimates disclaimer. Parameter coverage is adequate for most inputs, and annotations cover the safety profile. It is nearly complete, with only minor gaps such as source/return guidance left to the schema.

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 high at 83%, so the structured schema already carries most parameter meaning. The description adds useful context for savings/coast ('years until each country unlocks') and references portfolio and SWR, but it does not explain source or return, leaving those to the schema. This fits the baseline 3 for high schema coverage.

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 states a specific analysis and output: given a portfolio and SWR, it returns every country where passive income sustains defined lifestyle tiers. It is clearly a geo-arbitrage FIRE computation tool, but it does not explicitly contrast itself with adjacent siblings such as retire_on_budget, calculate_runway, or find_retirement_visas.

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?

Usage is implied by the input framing ('given a portfolio and safe withdrawal rate') and the outputs described, so an agent can infer it is for FIRE location analysis. However, there is no explicit when-to-use guidance, no exclusions, and no named alternatives among the many sibling tools.

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