create_session

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

With no annotations provided, the description carries the full burden of disclosing behavioral traits. It only states that the tool logs into a website and creates a reusable session, but does not mention credentials handling, session persistence, security implications, or potential side effects (e.g., server-side session creation). This is a significant gap for a tool that handles authentication.

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 concise (two sentences), front-loads the core action, and contains no redundant information. Every word serves a purpose, making it easy for an agent to parse quickly.

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?

The tool has a nested object (loginSelectors) and no output schema, yet the description does not mention what the tool returns (e.g., sessionId) or how the session is used with sibling audit tools. While the schema documents parameters, the description lacks high-level context about the workflow (e.g., the need to pass the session to audit_with_session). This is a moderate gap for a tool that serves as a prerequisite to other audit tools.

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 the baseline is 3. The description does not add any parameter-specific semantics beyond what the schema already provides; it does not explain how parameters like domain, username, or loginSelectors interact. The schema handles parameter documentation adequately, so no additional credit is warranted.

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 with a specific verb ('create') and resource ('reusable authenticated session'), and distinguishes it from sibling tools like audit_with_session by focusing on session creation rather than usage. It also mentions the purpose for audits of protected pages, which provides useful context.

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 usage context by noting the session is 'reused for multiple audits of protected pages,' which signals when to use this tool. However, it does not explicitly mention alternatives or exclusions (e.g., when to use audit_with_session directly with existing credentials), losing a point for not naming any sibling tool or alternative.

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