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

Goes well beyond the readOnly/idempotent/non-destructive annotations: states the call is free (no credits, no job), works with or without an API key on any plan, and returns live data matching the public pricing page. It also discloses the critical downstream rules (Pro/Studio required for API/MCP/CLI, 402 otherwise, per-generation credit costs, 'unlimited' is web-only, plans purchased in the web app not via API) that an agent needs before advising a user.

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?

Front-loaded with the core purpose and value proposition, and every clause carries actionable content — pricing scope, key gotchas, purchase channel, and freshness. It is dense rather than padded, though the long semicolon-delimited enumeration makes it heavier than a leaner version could be.

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?

No output schema exists, and the description compensates by enumerating exactly what is returned — all plans, both price intervals, credits, seats, concurrency, inclusions/exclusions, top-up brackets, per-call costs and policy rules. An agent knows precisely what it will get and how to use it.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate — the baseline of 4 applies. It correctly reinforces that no input (not even an API key) is required, which is the only invocation-relevant fact.

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?

Opens with a specific definition of the resource: 'What Ludo's paid service costs and includes,' then enumerates the exact payload (plans, monthly/annual prices, credits, seats, queue concurrency, top-ups, per-call cost, rules). No sibling tool returns pricing, so there is no ambiguity about which tool answers this question.

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?

Clear on when to call it: 'for an agent advising a user' about cost or before telling a user to pay, and clarifies it is a prerequisite lookup for API/MCP/CLI usage since those need a paid plan. It does not name a sibling alternative (e.g. getAccount, getDocs) or state when not to use it, keeping it short of a 5.

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