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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds non-obvious behavioral context: results carry an invitation_secret that is the prerequisite for accepting, which the agent could not infer from annotations alone. It stops short of describing pagination or result shape, so not a 5.

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 compact sentences with zero filler; the distinguish-from-sibling clause is front-loaded in the second sentence immediately after the purpose. 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?

An output schema exists, so return values needn't be explained, yet the description still surfaces the one output field that drives a downstream action (invitation_secret). Purpose, routing, and the accept/decline follow-up path are all present for this simple list tool.

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% – count, start and account_id all carry their own descriptions including defaults and the max. The description adds no parameter syntax or format meaning beyond that; the only detail it offers (invitation_secret) is a return value, not an input. 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 (List) and resource (pending connection invitations received by the account), plus a distinguishing scope detail ('received'). It explicitly separates itself from list_sent_invitations, so an agent can route correctly without opening either 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 a concrete when-to-use ('triage invitations waiting for the account'), names the downstream tools (accept_invitation, decline_invitation) in the right order, and names the sibling to use for the opposite case (list_sent_invitations). This is explicit when/when-not/alternatives guidance.

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