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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior, so safety is covered. The description adds meaningful context beyond that: the score is a transparent weighted sum, contributing facts appear in evidence[] with weights, coverage[] reveals which inputs existed, and the result is explicitly heuristic rather than authoritative.

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 and score range are front-loaded, and the inventory of scoring factors is compressed into one clause. It is dense but nearly every element (evidence[], coverage[], the heuristic disclaimer) carries information an agent would otherwise have to guess.

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?

An output schema exists, so return values need not be explained, yet the description still clarifies the shape of evidence[] and coverage[], which helps interpretation. Combined with the annotations covering safety, an agent has enough to invoke and read the tool correctly.

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?

Only one parameter and schema description coverage is 100%, so the schema carries the parameter burden (including the Brazilian registration format). The description adds only that one registration is scored, which is inherent in the purpose statement, so the baseline 3 is appropriate.

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 and resource: a 0-100 fit score for one registration against a fractional/shared-ownership program, and enumerates the scoring inputs. It is clearly a per-registration scoring tool, distinct from market-level siblings like jt_fractional_market, though no sibling is named explicitly.

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 scoring factors (owner role, fleet size, age, utilization, state, model category) but there is no explicit when-to-use guidance or routing to an alternative such as jt_fractional_market. The negative framing ('not an appraisal or an offer') narrows interpretation but does not tell the agent when to pick this tool.

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