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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds value by enumerating what comes back (quota, referral credits, invite link), which the agent can use to decide whether a call is needed. It does not state auth/prerequisite requirements for the invite link, which is the remaining gap.

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?

Two sentences with no filler: the first front-loads the return payload, the second gives the invocation conditions. Every clause 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?

With no output schema, the description carries the burden of describing return values and does so with three concrete items; annotations cover safety. Only the optional join_code pathway for brand-new members is left unexplained, a minor omission for a simple read.

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 join_code is already documented in the schema as originating from sign_up. The description never mentions the parameter or its optional/conditional nature, so it adds no meaning beyond the structured field — baseline 3 applies.

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 verb ('Return') and names the exact payload: remaining intro requests, friend-referral credits, and the personal invite link. This clearly separates it from siblings like get_my_profile or get_upgrade_link without needing to open a schema.

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?

Gives two explicit triggers: when the user asks how many requests remain, and after send_intro_request reports the limit. It names the sibling that produces the condition, so the routing decision is unambiguous.

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