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

With no annotations, the description carries the full burden, and it does disclose the key safety fact ('Read-only') plus the returned field set including masked email, which signals PII is partially redacted. It says nothing about pagination, result caps, sorting, or the time window covered, which matters for a list endpoint.

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?

A single compact sentence with the actor and scope front-loaded and the field list in a parenthetical; nothing is redundant and the read-only flag sits at the end where it reads as a qualifier.

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 zero-parameter list tool with no output schema, enumerating the returned fields is exactly the right compensation, and the read-only note covers safety. The remaining gap is operational: no hint about volume, ordering, or truncation behavior for what could be a large referral population.

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 takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The parenthetical enumerates outputs rather than inputs, which is useful but not a parameter concern.

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?

States a specific resource — people who signed up through the caller's referral links — and enumerates the data returned (masked email, link, signup date, free/paying, revenue, commission). An agent can distinguish it from create_referral_link / update_referral_link by the read/list framing, though it never explicitly names the nearest sibling get_referral_overview.

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 'list of people attributed to my referral links' framing implies when to reach for it, but there is no explicit statement of when to use it versus get_referral_overview or get_referral_share_card, and no prerequisites or exclusions. Usage is inferable but not spelled out.

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