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

Adds substantial behavior beyond the annotations: changes take effect live for every visitor, plan-gated settings are refused with the required plan, and the write is atomic ('nothing is written unless every value is valid'). These are exactly the destructive/idempotency implications an agent needs and are not derivable from destructiveHint/idempotentHint alone.

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 tight sentences, front-loaded with the action, then the input shape, then the two behavioral constraints that matter most (live effect, atomic validation). No sentence is wasted.

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?

Given a mutation tool with a nested-object parameter and no output schema, the description covers effect scope, validation, and plan gating well. It does not describe what a successful call returns or how partial/invalid keys are reported beyond the refusal behavior, leaving a minor gap.

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 both parameters are already documented in the schema. The description restates the object-of-name-to-value shape and adds the atomicity guarantee, but provides no syntax or key specifics beyond the schema itself, so the baseline 3 is appropriate.

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?

Starts with a specific verb+resource ('Change one or more chat widget settings') and immediately names the read counterpart it pairs with ('read them with get_widget_settings'). An agent can distinguish this mutation tool from its sibling read tool without opening either schema.

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 an explicit prerequisite ('read them with get_widget_settings first'), which is real usage guidance. It stops short of stating when not to use it or naming competing alternatives, so it falls short of a full 5.

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