zas_pair

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

With no annotations, the description carries the full burden and does well: it discloses that this is a stateful, multi-call flow, that re-approval replaces the prior agent, and the side effect that the owner sees every item this agent sends (with the >_ mark and agent name) on all devices. It omits auth/permission requirements and failure behavior, keeping it from a 5.

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 tight sentences with the core purpose front-loaded, then the protocol, the code branch, and the re-pairing case. The closing sentence about cross-device visibility is slightly tangential but still earns its place as behavioral context; nothing is redundant.

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 1-optional-param pairing tool with no output schema and no annotations, the description covers the interaction sequence, the code parameter's role, re-pairing semantics, and the resulting visibility. It is close to complete, missing only error/permission handling an agent might want.

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 100%, so the baseline is 3, but the description adds real value beyond the schema text: it explains the conditional trigger for `code` ('If the page shows a code, call again with `code`'), tying the optional parameter to a runtime condition rather than just its content.

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+resource: 'Pair this agent with a Zas account.' This is unambiguous and clearly distinct from the sibling send/receive/status tools, none of which handle account pairing. An agent can tell what this tool is for 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?

It lays out the multi-call protocol clearly: first call returns a URL for the owner, a later call reports approval, and a code-bearing page means calling again with `code`. It also notes the already-paired case (approval replaces the old agent). It stops short of naming explicit alternatives or when-not-to-call, but the when/how context is strong.

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