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

With no annotations, the description carries the full transparency burden. It discloses the critical gotcha that env vars don't suffice and that explicit invocation is mandatory, and clarifies the different key types for different scopes. While it doesn't describe the exact result of a successful auth (e.g., token storage), it provides substantial behavioral context beyond a simple 'authenticate' statement.

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 a compact paragraph of four sentences, but every sentence earns its place: purpose, prerequisite scope, key acquisition link, exception for global endpoints, env var caveat, and key type distinction. No filler or redundancy; it is appropriately structured for a critical auth tool.

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?

Given the complexity of an auth tool with multiple key types, no output schema, and no annotations, the description covers all essential aspects: when to use it, how to obtain the API key, which endpoints skip auth, the env var limitation, and the distinct roles of api_key vs master_key. It is self-sufficient for an agent to invoke 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?

The schema has 100% coverage on parameter descriptions, so baseline is 3. The description adds meaningful semantics beyond the schema: the env var warning, the relationship between tenant and api_key (format hint), and the explicit instruction to use master_key for cross-tenant operations. This elevates the parameter understanding beyond what the schema provides.

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 purpose: 'Authenticate with A-Team' and explicitly frames it as a prerequisite for tenant-aware operations. This distinguishes it from sibling tools, which are all domain operations, and the verb 'Authenticate' is specific and unambiguous.

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 provides explicit when-to-use guidance: required before tenant-aware operations, only global endpoints work without auth, env vars alone are insufficient, and master_key should be used for cross-tenant admin operations instead of api_key. It also gives a link for obtaining API keys, covering the practical usage context.

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