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

No annotations are provided, so the description carries full behavioral disclosure. It states that authentication returns tier/access level and that the key must start with 'wf_', which adds useful context. However, it does not disclose error behavior, session effects, or whether the key is validated against the server until invocation. This is adequate but not rich, warranting a mid-range score.

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 two sentences plus a well-formatted Args block. Every sentence earns its place: the first states the action and return, the second describes the parameter. No wasted words; structure is clear and front-loaded with the core purpose.

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?

For a one-parameter tool with no output schema, the description covers the essential context: what to provide (api_key) and what to expect (tier and access level). It lacks error handling or repeat-call guidance, but given the simplicity, it is sufficiently complete. A perfect score would require more operational detail, so a 4 is appropriate.

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 schema declares only 'api_key' as a required string with no description (0% schema coverage). The description compensates by explaining the parameter: 'Your WARN Firehose API key (starts with wf_)'. This adds meaningful format and ownership context beyond the schema. It could go further (e.g., where to obtain the key), but the provided hint is valuable.

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 clearly states the tool's function: 'Authenticate with your WARN Firehose API key.' It uses a specific verb ('Authenticate') and resource ('API key'), and it distinguishes itself from sibling data-retrieval tools by being an authentication utility. It also mentions the return value (tier and access level), reinforcing its purpose.

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?

The description implies this is a prerequisite for other API interactions (authentication), but it does not explicitly state when to use it versus alternatives. Since all sibling tools are data queries, it is clear this is the auth gate, yet the description lacks explicit 'use this before other calls' guidance. Score reflects implied but not explicit usage context.

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