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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so safety and idempotency are covered structurally. The description's added content is largely a list of returned state categories, which the output schema already exposes, and it says nothing about auth/prerequisite conditions or what happens when no membership or migration exists. With annotations carrying the safety profile, a 3 reflects modest added value.

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, front-loaded with the action and scope, with the sibling comparison placed last where it aids selection. Minor redundancy: the enumerated state categories partially restate what the output schema already returns, but they let an agent triage relevance in one pass.

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 an output schema exists, the description need not document return values, and annotations plus the zero-parameter schema cover the invocation mechanics. It is complete enough to call correctly, with only the absence of failure/empty-state behavior (e.g., no membership yet, pending migration) keeping it from the top mark.

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; the baseline for a 0-param schema is 4. The description correctly signals that the call is unparameterized by framing it as reading 'this agent's' identity, with no selector argument implied.

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?

Specific verb plus resource ('Read this agent's identity state') followed by an enumeration of what that state contains (membership, verification/migration state, creation authorization, next steps, identity links). It also names the nearest sibling, kellian_get_me, and states the axis on which it differs, so an agent can distinguish the two 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?

The clause 'Richer than kellian_get_me for identity linking' gives a concrete selection rule: prefer this tool when identity linking detail matters. It stops short of an explicit 'use kellian_get_me instead when you only need basic profile data', so the routing is implied rather than fully spelled out.

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