x402_session_fetch

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

With no annotations provided, the description carries the full burden and does well by disclosing key behaviors: it automatically attaches the session token, grants access without payment, and returns an error for expired sessions. However, it lacks details on rate limits, authentication needs beyond the session, or what specific errors might occur, leaving some gaps.

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 front-loaded with the core purpose in the first sentence, followed by essential context and error handling. Every sentence adds value—no wasted words—and it's structured logically from usage to prerequisites to error resolution.

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 tool's complexity (session-based HTTP requests with 6 parameters), no annotations, and no output schema, the description is mostly complete. It covers purpose, usage, prerequisites, and error handling, but lacks details on return values or advanced behavioral traits like rate limits, which would be helpful for full completeness.

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 schema already documents all parameters thoroughly. The description adds minimal value beyond the schema, only implying that the URL must be 'covered by the session' and noting automatic token injection, but doesn't provide additional syntax or format details. Baseline 3 is appropriate as the 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 ('Make an HTTP request within an established x402 V2 session') and resource (session-based HTTP requests), distinguishing it from siblings like x402_session_start (which creates sessions) and x402_pay (which involves payments). It explicitly notes 'NO payment required' to differentiate from payment-related tools.

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 guidance on when to use this tool ('within an established x402 V2 session'), prerequisites ('Requires a session_id from x402_session_start'), and alternatives for errors ('call x402_session_start again to renew'). It also clarifies when not to use it ('NO payment required'), distinguishing it from payment tools.

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