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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds real behavioral context beyond that: the Enterprise-on-quote fallback above the largest plan, the four possible status values, and the fallback behavior ('contact address given') when no public fact exists. Pagination/side effects are irrelevant for a read-only check, so this is strong.

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 is front-loaded in the first sentence, followed by inputs and then return values in a logical order. The return-value sentence is long and dash-heavy, but nearly every clause carries information an agent needs.

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 no output schema, the description carries the burden of explaining return values, and it does so thoroughly: plan selection, prerequisites, per-need status taxonomy, known gaps, and trial link. Minor gaps remain around how free-text needs are matched and what 'see_facts' entails.

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 coverage is 100% and the schema already documents needs keys, free-text fallback, language enum, size bounds, and provider enum. The description largely restates the parameter list ('company size, mail provider, up to 20 needs') without adding syntax or format meaning, so baseline 3 applies.

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 resource ('fit check for one company') and enumerates what comes back: plan for the size, mail prerequisites, per-need statuses, gaps, and trial link. It is clearly narrower than siblings like get_pricing or get_overview, though the verb 'fit check' is slightly informal.

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?

It notes that all inputs are optional, which implies you can call it with partial data, but it never says when to prefer this over get_pricing or get_deliverability_prerequisites despite their overlap. Usage is inferred rather than stated.

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