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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds a meaningful behavioral fact beyond that — no authentication is needed — which an agent cannot infer from the annotations. It stops short of noting caching or response freshness, a minor gap.

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?

Three short clauses, front-loaded with the resource and the 'use first' guidance. Every sentence carries distinct information: what it fetches, the auth characteristic, and when to call it.

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 explain return values, and it still summarizes the payload's purpose ('learn what tools and APIs are available'). No parameters plus full annotation coverage means nothing an agent needs to call this correctly is missing.

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 input schema has zero parameters, so there is nothing the description needs to disambiguate; per the baseline this lands at 4. The description correctly implies a parameterless call.

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 gives a specific verb and resource — 'fetches llms.txt' and 'discover the platform's public capabilities' — and scopes it as public/no-account, which distinguishes it from account-gated siblings like register_account or list_llm_keys. An agent can tell what this returns without opening the schema.

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?

'No account required. Use this first to learn what tools and APIs are available' gives clear timing and a prerequisite-free context for invocation. It does not explicitly contrast with the closest alternative, get_onboarding_guide, leaving the agent to infer which discovery/onboarding entry point to pick.

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