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

With no annotations, the description carries the behavioral burden. It discloses authentication needs, the fact that the proof token appears only once confirmed, and that polling is expected. It does not cover not-found/error handling or status values, but these are minor for a simple getter.

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?

The first paragraph is front-loaded and directly describes behavior. The second ACCESS paragraph is extra operational context, somewhat verbose with all-caps formatting, but it earns its place by warning about auth and the start_login pitfall.

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 one-parameter read with no output schema, the description covers the essential selection/invocation needs: what the tool does, auth prerequisite, and what it returns. It leaves some ambiguity about source of the ID and exact status values, but those are not blockers.

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 schema already describes the only parameter (Identity challenge ID) at 100% coverage, and the description adds no additional semantics beyond restating lookup-by-ID. Baseline 3 is appropriate when the schema documents the parameter fully.

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 opening sentence uses a specific verb and resource: 'Get a Proof-Me identity challenge by ID.' It also states what is returned (status, the CONFIRM channel, and proof token once confirmed), which clearly distinguishes it from the create/list siblings and other get_* tools.

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?

It gives clear use context: 'Poll this for resolution' identifies this as the polling/read step, and the ACCESS note states an authentication prerequisite before calling again. It excludes start_login as a way to open this tool, though it does not name alternative tools beyond that path.

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