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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds valuable context by enumerating the specific data returned and explicitly confirming that no payment or withdrawal is triggered, reinforcing the non-destructive nature beyond the 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 concise, listing the key data items in a single sentence followed by a clear safety note. It's front-loaded with the main purpose. Minor redundancy: the safety note complements rather than repeats the annotations, so it earns its place.

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 low complexity (1 optional param, no output schema), the description is complete: it enumerates the data returned, confirms non-destructive behavior, and the schema covers the authentication parameter. An agent has enough to call it correctly without needing more detail on return format.

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 100%, so the single optional parameter agent_key is fully documented in the schema, including its format and security guidance. The description doesn't add anything about the parameter, but with complete schema coverage, the baseline of 3 is appropriate.

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 lists all the referral-related data it returns (referral code, participation proof, referred registrations, etc.), making the tool's purpose specific and unambiguous. It distinguishes itself from siblings like speedbot_referral_join and speedbot_referral_program by focusing on status/read, though it doesn't explicitly name those alternatives.

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 is a read-only status check, and the explicit note 'No payment or withdrawal is triggered' suggests when it's safe to use. However, it doesn't explicitly state when to use this tool over speedbot_referral_program or speedbot_referral_join, nor does it provide conditions or exclusions (e.g., 'use speedbot_referral_join to start participating').

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