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

Annotations declare readOnlyHint=false, destructiveHint=false, openWorldHint=false, confirming a non-destructive write confined to the form. The description adds useful behavioral context — the field is seeded from URL params and submitted with the form, and is referenceable in defaultValueFieldRef, logic conditions, and calculateValue refs. It doesn't cover ordering side effects (after vs position), idempotency, or what happens to existing fields. With annotations present the bar is lower, so a 3 is fair.

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?

Two sentences, front-loaded with the core action and then the intended use cases. It is appropriately sized for the tool and has no filler. The second sentence is dense but each element (URL params, defaultValueFieldRef, logic conditions, calculateValue) is meaningful.

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 write tool with no output schema, the description covers purpose and the referenceable-value behavior, but omits the insertion-position nuance (after vs position cannot be combined) which is critical to correct invocation. The sibling differentiation is also absent, leaving an agent to choose between editor_insertVariable, editor_insertCalculatedField, and this tool without explicit guidance.

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 all six parameters already carry descriptions, including the positional 'after'/'position' semantics and the paramName pattern. The description adds no additional parameter detail beyond this. Baseline 3 applies when the schema does the heavy lifting.

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 specific verb ('insert') and resource ('hidden metadata field'), and goes beyond by naming use cases (URL param seeding, form submission). It doesn't explicitly differentiate from siblings like editor_insertVariable or editor_insertCalculatedField, which have overlapping roles for referenceable values, leaving some ambiguity.

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 a purpose and example use cases ('recipient IDs, campaign tags, attribution data') but does not state when to prefer this over editor_insertVariable or editor_insertCalculatedField, which are the closest functional siblings. An agent still has to infer the choice.

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