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

Annotations only mark this as a non-read-only, non-idempotent, non-destructive operation. The description goes well beyond that by disclosing side effects (account + API key creation), the lack of email verification, optional email purpose, the 'zs_live_' key prefix, the required Authorization header, and the 0-credit initial state. This is rich behavioral context that annotations do not provide.

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?

Three dense sentences deliver the core purpose, authentication usage, and next-step workflow with no filler. Each sentence earns its place, and the most important information—account and API key creation—is front-loaded.

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 there is an output schema, the description does not need to describe the return value. It covers prerequisites (none), credential usage for all other tools, initial credit state, and the immediate next actions. The tool is fully callable and integrable from this description alone.

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 must compensate. It adds real meaning for email ('optional, receipts/recovery only'), but it says nothing about the name parameter beyond what the schema's 'Name' title already implies. Because one of two parameters gains semantic context while the other remains minimally documented, a 3 is appropriate.

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 states a specific verb and resource: 'Create a zSign account and API key in one call.' It also clearly separates this tool from siblings like get_pricing and buy_credits by framing it as the account-provisioning entry point. Including the API-key creation detail removes any ambiguity about what the tool returns.

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 description gives strong contextual guidance: account creation requires no email verification, and new accounts start with 0 credits, followed by 'call get_pricing then buy_credits next.' It stops short of explicitly stating when not to use this tool or naming alternative account-related tools, but the flow is clear enough for an agent to sequence correctly.

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