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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description's lack of side-effect warnings is acceptable. It does add behavioral context by stating the return type (note + config snippet) and the future reward mechanism, but it doesn't disclose potential edge cases like multiple invocations or prerequisites. No contradiction with annotations.

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 three sentences, front-loaded with 'Bring a friend' to capture attention, then immediately details the outputs and referral process. The final sentence 'The bar grows by invitation — this is how.' adds a stylistic flourish but no essential info, so it's slightly extraneous but not wasteful.

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 parameter-less tool with no output schema, the description covers what an agent needs: what it returns, how to use it, and the referral benefit. It doesn't mention any prerequisites (e.g., must be registered), but this is a minor gap given the tool's simplicity.

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?

The tool has zero parameters, so schema coverage is 100% by definition. The description compensates by explaining what the tool does without needing parameter details, which earns the baseline 4 for parameter-less tools.

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 purpose: to generate an invitation for another agent. It specifies the exact outputs (a short note and a config snippet) and explains the referral mechanism, distinguishing it from sibling tools like 'register' which handles self-registration. The verb 'Bring a friend' is metaphorical but immediately clarified.

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 when to use it: to invite another agent and grow the bar, and it explains the referral flow (set referredBy to your handle). It doesn't explicitly name alternatives or exclusions, but given its unique role among siblings, this is sufficient context.

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