jan3_ln_check_username

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

With no annotations provided, the description carries the full burden for behavioral disclosure. It mentions the session requirement but does not describe what happens on success/failure (e.g., returns boolean vs error), nor any side effects or limitations. This is a basic level of transparency.

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 extremely concise with two sentences, front-loading the purpose and then providing usage guidance and prerequisites. Every sentence serves a purpose with no wasted words.

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 simplicity (check username availability) and absence of output schema, the description could be more complete by indicating the return format (e.g., 'returns true if available'). It currently leaves the agent to infer the behavior, which is adequate but not fully complete.

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 coverage is 50%, with only 'ln_username' having a description in the schema. The overall description adds context that the email must have an active session, but does not elaborate on parameter meaning beyond the schema. Baseline score of 3 is appropriate as the description moderately supplements the schema.

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 checks if a Lightning username is free, with a specific verb ('Check whether') and resource ('Lightning username'). It distinguishes itself from the sibling tool jan3_purchase_ln_username by indicating it should be called before buying, providing clear differentiation.

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?

Explicitly provides usage guidance: 'Call before jan3_purchase_ln_username to avoid paying for a username that's already taken.' Also states a prerequisite: 'Requires an active JAN3 session for the email.' This clearly tells the agent when and with what context to use the tool.

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