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

With no annotations, the description carries the full burden and does substantial work: no regex support, pages over 256 KB fail as 'size', the callback reports only the failing condition name and never page content, plus concrete rate/cost tiers. It omits auth requirements, retry/failure behavior, and lifecycle (how the watch is cancelled or inspected, despite a watch_cancel sibling), which keeps it short of 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?

Everything is front-loaded: trigger semantics first, then expect grammar, then failure modes, then cost, then a concrete example. The telegraphic style ('No regex.', '2c/day at >= 60s') is dense but each fragment carries unique information with no filler.

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 tool with a nested free-form object parameter, no output schema, and no annotations, the description supplies the assertion grammar, the size failure mode, the callback payload contract, and pricing. What is missing is the target/callback_url contract (URL format, HTTP method/payload shape) and the watch lifecycle, which siblings like watch_cancel/watch_get presumably handle.

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 0% and the key parameter is an opaque nested object with additionalProperties:true, yet the description fully specifies its grammar: 1-5 conditions of status (int), contains/not_contains (string or list), and json_path (dotted, e.g. "data.items.0.state") with equals (JSON scalar) or exists (bool). interval_s is only implied via the pricing thresholds, and target/callback_url are left as bare names.

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 opening line states a specific trigger condition for a content-based watcher ('Fire when a URL answers but says the wrong thing'), which is far more informative than a name restatement. It never names a sibling (watch_register, overrun_watch, deadman_checkin) to distinguish this content-checking watch from the other watch tools, so the reader must infer the 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?

Usage is implied rather than stated: the expect grammar and the pricing tiers (2c/day at >=60s, free within the first 5 at >=300s) tell the agent this is for recurring content assertions, but there is no explicit when-to-use/when-not or pointer to an alternative watch tool. The worked example is the only concrete invocation guidance.

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