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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds the useful default ('all' when direction is omitted) but says nothing about result size, pagination, or ordering beyond what the output schema provides.

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 front-loaded sentence with parenthetical clarifications that each earn their place; no filler. The parenthetical explanations are dense but readable.

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 read-only list tool with zero required parameters and an output schema that documents return values, the description covers what is listed and how to filter. Only minor gaps remain (no mention of ordering/pagination).

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 0%, so the description carries the burden and partially compensates: it explains the meaning of each direction value and that 'all' is the default, and marks group_id as an optional filter. It does not explain the UUID format or any constraints beyond optionality.

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 resource (invitations) and enumerates the three scopes it can return (received, sent, all), which lets an agent understand exactly what is listed. It doesn't explicitly contrast itself with siblings like get_inbox or respond_invite, so it lands just short of a 5.

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?

Usage is implied (list your invitations, optionally filtered by group), but there is no explicit when-to-use or when-not-to-use guidance and no mention of the alternative sibling tools (e.g., get_inbox, respond_invite). The agent can infer intent but gets no routing help.

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