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

Annotations only declare write/non-idempotent/non-destructive; the description adds substantial behavioral context beyond that — the plan entitlement gate, a hard rate limit (20 active alerts per key), the asynchronous side effect (a POST to webhook_url when a matching transaction appears), and the credit cost. This is exactly what the description is for.

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?

Information is front-loaded (purpose, then requirements, then inputs, then behavior, then cost) and every line earns its place. Required vs optional grouping makes the constraints scannable with no redundant prose.

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 write tool with no output schema, the description covers the entitlement, quota, required inputs, the webhook delivery behavior, and cost. An agent has everything needed to decide whether and how to call it; the lack of an output schema is adequately compensated by the stated side effect.

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 the cross-field rule that at least one location filter (code_postal, commune, code_departement) is required — a conditional constraint the schema only encodes piecemeal — and separates required from optional params.

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 first sentence states a specific verb (create) plus resource (webhook alert) and the trigger condition ('new DVF transactions matching your criteria'). The name and description cleanly separate it from list_market_alerts, update_market_alert, and delete_market_alert without needing 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 gives real context for using this tool: Pro/Enterprise plan required, max 20 active alerts, and the required inputs. However, it never routes the agent to alternatives (e.g. use update_market_alert to modify an existing alert, list_market_alerts to view current ones), so the sibling comparison is left implicit.

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