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

Annotations declare non-read-only, non-idempotent, non-destructive, but the description goes well beyond by disclosing the key prefix (zs_live_), the auth header format, that unverified accounts stay at 0 credits due to an anonymous-abuse guard, and the credit-unlock consequence of verification. This is exactly the behavioral context annotations cannot carry.

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?

Front-loads the core action and key deliverable, then layers constraints and next steps. Slightly dense with the verification flow, but every sentence carries actionable information; the endpoint reference could arguably be trimmed.

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 provisioning tool with an output schema present, the description covers what the agent needs: what is created, the key format, where to use it, the credit state and how to change it, and the immediate next tools. Complete given the output schema handles return values.

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 coverage is 0%, so the description must compensate. It clarifies email semantics ('Email is optional', verification implications) but says nothing about the 'name' parameter. Partial compensation for a 2-param tool, but one parameter is left entirely undescribed. Baseline for low coverage is not met 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?

States a specific verb and resource ('Create a zSign account and API key in one call') and distinguishes itself from every sibling, which are all downstream envelope/credit operations. An agent can identify this as the entry-point provisioning call without opening the 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?

Explicitly routes the agent: create here first, then send_envelope works, then buy_credits when more credits are needed. Also states the email-verification path for unlocking starting credits, which is a when/when-not condition tied to a concrete outcome.

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