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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description reinforces this with 'Creates no watch, no baseline, no diff.' It adds behavioral details beyond annotations by specifying the report content: 'what was captured + whether the page is reachable (and the text a text-watch would compare).' 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 description is four sentences that front-load the purpose ('Dry-run a watch config BEFORE creating it'), then add critical side-effect information and usage guidance. It is concise, with no wasted words or repeated schema content.

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 has no output schema, so the description carries the burden of explaining return values. It covers key aspects: 'what was captured', 'whether the page is reachable', and 'the text a text-watch would compare', plus 'Returns JSON'. However, given the complexity (10 params, nested renderParams), a more explicit output structure or further details would make it more complete, but it is adequate for a dry-run validation tool.

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 baseline is 3. The description's mention of 'render the proposed config once' and 'text a text-watch would compare' loosely references renderParams and diffMode, but it does not add meaning beyond the schema's thorough per-parameter descriptions. The schema already documents all parameters in detail.

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 clearly states the tool's purpose: 'Dry-run a watch config BEFORE creating it'. It uses a specific verb ('dry-run') and resource ('watch config'), and distinguishes itself from siblings by explicitly stating 'Creates no watch, no baseline, no diff', which differentiates it from watch_create and watch_run.

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 clear usage context: 'BEFORE creating it' and 'Use this to validate a selector/scope/identity first.' It implies the alternative is actual creation, and the sibling list includes watch_create and watch_run, which helps disambiguate. However, it does not explicitly name alternatives or state when not to use it.

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