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

Adds real context beyond annotations: 'Overwrites the given fields; previous values are not kept' corroborates destructiveHint=true, and the quota note ('uses plan quota') discloses a cost side effect not captured by any annotation. This is genuinely useful behavioral disclosure, though it stops short of return/permission details.

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 core statement ('Update an existing monitor') is buried behind an opening sentence about daily scheduled prompts and plan quota, which is context rather than the operation. The overwrite vs. omitted-keeps-value statements are both present and slightly redundant, diluting a description that could be tighter.

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 output schema, the description covers the partial-update contract and the tricky platforms/country validation rule, which is what an agent needs to call it correctly. It omits error/return behavior, but no output schema exists to lean on.

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?

With 100% schema coverage the baseline is 3, but the description adds cross-field semantics the schema lacks: platforms-without-country are validated against the stored country, and country-without-platforms must be supported by all existing platforms. This is meaningful behavior beyond the schema.

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?

States a clear verb+resource ('Update an existing monitor'), and the surrounding sentences establish it operates on monitors with name/country/language/platforms/is_active. It is distinguishable from create/delete-monitor siblings by the explicit 'existing' framing, though it does not name those alternatives directly.

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?

Gives concrete usage guidance: 'Every field is optional, so send only the fields to change; a field that is omitted keeps its current value.' It also explains the conditional validation between platforms and country, telling the agent how to compose valid input. No explicit when-not-to-use or sibling routing, so not a 5.

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