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

With no annotations, the description carries the full behavioral burden and does much of it: quota limits, 30-day TTL, one-time secret return that cannot be retrieved again, and the delivery/management model. It omits auth requirements for registration and what happens when quotas are exhausted, but the disclosure of limits and irreversible secret handling is well above average.

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 what-and-why is front-loaded in sentence one, followed by trigger semantics, limits, secret handling, and management in a compact block. Every sentence carries information, though the middle sentences could be tightened slightly.

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 mutation tool with no annotations and no output schema, the definition covers triggers, quotas, TTL, secret lifecycle, and follow-up management paths. It stops short of stating registration prerequisites (auth) or the shape of the registration response, but an agent has enough to invoke it correctly.

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 description coverage is 100%, so the schema already documents spec, secret, fire_cap, and callback_url, including detailed spec examples and the SSRF guard. The description only marginally reinforces the one-time secret behavior, adding little beyond the structured fields — the baseline 3 applies.

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 and resource: 'Register a free webhook subscription.' It immediately distinguishes itself from every sibling tool, none of which deal with webhooks, and the parenthetical list of trigger types (price drop, status change, rank shift, macro threshold) further pins down what the watch does.

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 clearly establishes the context of use (subscribe to push deliveries when a spec fires) and reveals the free-tier constraints (5 watches per IP, 25 fires, 30-day TTL) plus a pointer to management endpoints. It gestures at a paid alternative ('same delivery infrastructure as paid /api/premium/watches') but never states when an agent should prefer the paid path, so the alternative routing is implied rather than explicit.

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