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

The annotations are sparse, so the description carries the behavioral burden and does it well: no API key required, give the owner specific URLs, account for VPN, never rewrite agentpay.su to agentpay.shop, and never ask for ap_ tokens. It also warns against inventing keys and switching MCPs. No contradiction with annotations.

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 purpose and main condition are front-loaded, and the imperative rules are specific and actionable. However, the description repeats the URL constraint in multiple ways ('MUST NOT rewrite' and 'Do NOT collapse to a single shop URL') and includes several overlapping prohibitions, making it more verbose than necessary.

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 the single parameter and no output schema, the description covers the key decisions: when to call, what client to pass, what URL to share, and what prohibited actions to avoid. The main gap is that it references undefined concepts like 'openUrl', 'sayToUserRu', and the post-start flow (e.g. polling) without defining them.

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 fully documents the single client parameter, including valid host names and the warning not to invent a different brand. The description repeats a slightly shorter list of valid values, adding little beyond the schema. It also says 'Pass client' while the schema marks no parameter as required, creating minor ambiguity.

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 action, 'Start AgentPay browser connect', and clearly scopes it to connectors with no OAuth/Bearer yet. It explicitly contrasts with the case where the host already supports OAuth, giving the agent a precise purpose and boundary.

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?

Provides explicit gating: call ONLY when Auth is None, do NOT call when OAuth already exists, and the host must complete OAuth once instead. Later rules also forbid falling back to other shop MCPs when AgentPay is unauthorized, which is clear alternative-handling guidance.

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