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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the mutation/safety profile is covered structurally. The description adds one useful behavioral fact — field_id is auto-generated if omitted — but does not say whether field_type is immutable after creation, how ID collisions are handled, or what permissions the create requires.

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 one-line purpose is front-loaded and the Args block is scannable with no filler. Some entries are terse ('The project ID.') but nothing is wasted or redundant.

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?

An output schema exists, so return values needn't be described, and the parameters are fully covered. What's missing for a create-in-collection operation is ordering/prerequisite context and whether the new field type constrains existing or future items — relevant given the paired create_directory_item and update_directory_field tools.

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 0%, so the description carries the full parameter burden, and it does so: it documents all five parameters, including the optional field_id default. Critically, it enumerates the valid field_type values (text, richtext, image, link, datetime, switch, option, reference, map, html, multiimage, video), which the schema does not expose as an enum — without this an agent could not construct a valid call.

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 first sentence states a specific verb and resource: 'Create a new field in a directory collection.' That distinguishes it from create_directory_collection, create_directory_item, and update_directory_field in the sibling list. It doesn't explicitly name or contrast those siblings, so it stops short of a 5.

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?

There is no guidance on when to choose this tool, what prerequisites exist (e.g., the collection must already exist), or when to prefer update_directory_field. The agent must infer all of this from the name and the directory_* sibling cluster.

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