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

With no annotations supplied, the description carries the full behavioral burden. It does valuable work by disclosing that both keys are returned only once, which warns the agent not to expect a re-fetch, but it omits permission/auth requirements, whether the caps are editable after creation, and what happens if registration is repeated with the same label. That leaves meaningful behavioral gaps for a mutation tool.

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?

Four short, front-loaded sentences with no filler; the critical one-time key return is stated early. The telegraphic fragments ('It sets spending caps') are efficient but border on under-specified rather than merely concise.

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 3-parameter creation tool with no annotations and no output schema, the description covers the most agent-critical fact, that keys are returned once and the human key must be handed off. It is still incomplete on label semantics, cap units, null handling, and post-creation mutability, which an agent would need to invoke it correctly.

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% for all three parameters, so the description must compensate and largely fails to. 'It sets spending caps' vaguely gestures at daily_cap and voucher_cap without explaining units, currency, or what null means, and the 'label' parameter is never mentioned at all, so its purpose is undocumented everywhere.

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 opens with a specific verb and resource ('Create an agent') and adds the salient output artifacts (api_key with pwp_ prefix, human_key with pwph_ prefix). It does not explicitly distinguish itself from siblings like issue_voucher or claim_sandbox, but the verb+resource pair is unambiguous on its own.

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?

There is no statement of when to register an agent versus using an alternative, no prerequisites, and no conditions or exclusions. The only procedural guidance is a post-call instruction ('Give the human key to the human'), which is workflow advice rather than usage-selection guidance.

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