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

With no annotations provided, the description carries full burden for behavioral disclosure. It mentions browser automation and headless mode, but lacks critical details: whether authentication persists across sessions, what happens on failure (e.g., error responses), rate limits, or security implications. For a sensitive authentication tool, this is a significant 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?

The description is a single, efficient sentence with zero waste. It front-loads the core purpose ('Authenticate with Costco account') and includes essential method details without unnecessary elaboration.

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 authentication (sensitive operation with browser automation) and no annotations or output schema, the description is insufficient. It omits behavioral traits like session persistence, error handling, or security warnings, leaving critical gaps for agent decision-making.

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%, so parameters are fully documented in the schema. The description adds no additional meaning beyond implying email/password are for Costco accounts, which the schema already states. Baseline 3 is appropriate when schema does the heavy lifting.

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 specific action ('Authenticate'), target resource ('Costco account'), and method ('using email and password via browser automation'). It distinguishes from siblings like 'logout' or 'get_membership' by focusing on initial authentication rather than session management or data retrieval.

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 tool should be used for initial authentication, but provides no explicit guidance on when to use it versus alternatives (e.g., whether it's required before other tools like 'add_to_cart'), nor any prerequisites or exclusions. Usage context is inferred rather than stated.

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