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

With no annotations, the description carries the full burden. It states the core behavior (authenticate and return token) but does not disclose failure modes, token expiration, or any side effects (e.g., invalidating existing sessions). This is adequate but not rich.

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?

Two sentences, no unnecessary words. The first sentence starts with the action verb, and the second explains the return value. Perfectly concise.

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 simple authentication tool with no output schema, the description covers the essential purpose and return value. It could add more detail about token usage or error handling, but it is not required for tool selection given the simplicity of the operation.

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 description coverage is 100% for both parameters, so the schema fully defines 'email' and 'password'. The description adds no additional parameter-level meaning beyond what is already in the schema, matching the baseline of 3.

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 uses a specific verb 'Authenticate' and identifies the resource (email and password) and the outcome (session token). It clearly distinguishes this from all sibling tools, which are focused on courses, concepts, and study activities, not authentication.

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 phrase 'for subsequent requests' implies this should be used before other API calls, giving clear context. However, it does not explicitly mention when not to use it or mention any alternative tools, though none exist among siblings.

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