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

Annotations are all false (readOnly, openWorld, destructive), so they carry no safety or mutation signal. The description compensates fully: it explains that the tool creates or recovers a session, returns an openUrl that must be shared immediately, requires polling with linkSessionId, and handles AGENTPAY_API_KEY retry logic. It also discloses that the tool takes no phone number and that the phone number never enters chat, which is critical behavioral context. No contradictions 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?

Although long, every sentence earns its place. The description is front-loaded with the purpose and triggers, then flows logically: reuse condition, forceNew condition, openUrl handling, phone avoidance, polling, auth retry, and explicit 'never' instructions. There is no fluff; the density is justified by the auth-flow complexity. It is structured as a procedural guide, which is appropriate for a tool that orchestrates a multi-step interaction.

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?

The tool is a session-initialization step in a larger flow, yet the description covers the full lifecycle: when to call, what it returns (openUrl), how to proceed (poll_dixy_call_auth), how to handle auth errors (AGENTPAY_API_KEY with sessionId), and what not to do. With no output schema, the description must explain return usage, and it does. The presence of sibling tools like poll_dixy_call_auth and begin_agent_link is addressed, so an agent can navigate the whole sequence without missing steps.

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%, but the description adds substantial meaning beyond the schema: forceNew is explicitly conditioned on prior server errors (DIXY_REAUTH_REQUIRED or DIXY_WEB_SESSION_REQUIRED), and sessionId is tied to the agent-link flow and the absence of a Bearer token. These are not in the schema and are essential for correct parameter usage. The description elevates the parameters from simple types to actionable rules.

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 ('Create or recover the secure Dixy sign-in') and immediately ties it to concrete triggers: when current prices, budget, availability, cart or checkout are needed. It distinguishes itself from siblings by naming poll_dixy_call_auth as the follow-up and by stating when to use forceNew. The purpose is unambiguous and differentiates this from the many other tools in the sibling list.

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 explicit when-to-use triggers (prices, budget, availability, cart/checkout) and when-not-to-use guidance: if already linked, reuse it; forceNew only after DIXY_REAUTH_REQUIRED or DIXY_WEB_SESSION_REQUIRED. It also gives negative instructions (never ask for phone in chat, never begin_agent_link again, never edit connector settings). This fully routes the agent through the correct flow and away from pitfalls.

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