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

Beyond the annotations (which already declare non-read-only, idempotent, non-destructive), the description adds the write scope, the permission model, plan gating, a human-confirmation requirement, and the fact that only the fields sent are changed. It also cites the underlying PATCH endpoint, which is useful audit context.

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?

Front-loaded with a bracketed scope marker, then the mutable fields, then the constraints, in roughly two dense sentences. The inline enum restatement is mild redundancy with the schema but the text stays compact and scannable.

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?

Covers permissions, plan entitlement, cost, confirmation workflow, partial-update behavior, and the wrapped endpoint — enough for an agent to call it safely without an output schema. It does not describe the response body or whether changing ctaLevel has retroactive effects on existing posts, which would complete the picture.

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 100%, so the enums and defaults are already fully documented; restating "ctaLevel (off, warn, block)" and "ctaPaidLevel (warn or block)" adds little. The one genuine addition is "changes only the settings sent," which tells the agent that omitted fields are left untouched — important given zero required parameters — but it is a single insight against a otherwise schema-covered surface.

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?

"Changes only the CTA check settings sent" gives a specific verb plus resource and signals partial-update semantics, and the four named fields (ctaLevel, ctaPaidLevel, organicSupportingHosts, autoApplyPrimaryCta) pin down the scope. It stops short of naming the sibling it is not (cta_settings_get, cta_check), so an agent must infer the distinction from the names.

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?

Provides real preconditions: only brand owners/admins may call it, the Pro plan or higher is required, it is free, and the user should confirm changes first. It does not explicitly compare against alternatives such as cta_settings_get or cta_check, but the operational context for when to call it is clear.

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