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

Annotations already declare a non-readonly, non-idempotent, open-world write, and the description adds genuinely new behavior: plan-imposed caps, and an enumerated refusal taxonomy (monitor_limit_reached, monitor_exists, invalid_url, invalid_parameter) delivered as a tool error. The note that a repeat create answers monitor_exists rather than double-creating is valuable retry semantics. It still doesn't say what a successful call returns.

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?

Four short sentences, zero filler, and the most decision-relevant facts (plan constraints, refusal codes, repeat-call semantics) are front-loaded. Nothing is restated from the schema.

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 32-parameter creation tool with no output schema and no annotations covering return values, the description never says what comes back on success (e.g. the created monitor's id/object), which the agent needs to chain into monitor_update or monitor_pause. Error handling and plan behavior are well covered, so the gap is narrow but real.

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 88%, so the schema already carries parameter meaning for nearly all 32 fields, and the baseline is 3. The description only reinforces the plan-driven behavior of monitor_limit, interval_minutes and check_regions; it adds no per-type or format detail 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?

The description opens with a specific verb+resource, "Create a monitor", which is unambiguous against its siblings monitor_get, monitor_list, monitor_update, monitor_pause and monitor_resume. It doesn't explicitly name a sibling to distinguish itself from, but the CRUD family makes the role self-evident.

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 useful operating context — plan limits on monitor count, minimum interval and regions — but never states when to use this versus monitor_update (e.g. 'use monitor_update to change an existing monitor'), nor any prerequisite beyond the plan. Usage is implied rather than directed.

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