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

Annotations already disclose write, non-idempotent, non-destructive, closed-world behavior, so the bar is lower. The description usefully adds the reserved-namespace rule ('lf_'/'icp_' are HelpWell's own), but it says nothing about what happens on a repeat call for a non-idempotent write, whether an existing field name errors, or permission requirements.

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 action and immediately followed by the constraint that matters most. Dense but every clause carries information; the first sentence is slightly run-on but nothing 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?

For a four-parameter mutation with no output schema and thin schema coverage, the description covers the concept and reserved keys but omits conflict/error behavior and the meaning of the non-idempotent write. Enough to attempt the call, not enough to predict its failure modes.

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 only 25% (only 'field' documented), so the description has to compensate. It does add real value for 'field' via the reserved-prefix rule and explains the purpose of 'type' ('so segments, journeys and personalization treat it right'), but 'label' and 'description' remain undocumented and the seven enum values are never characterized.

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+resource ('Create a contact field') and distinguishes two distinct modes: pre-declaring a field before its first value, and pinning a guessed field to a type. It reads clearly against near-neighbours like list_fields and unlock_field, though it never names them explicitly.

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 two clauses imply when each mode applies ('ahead of its first value', 'lock a guessed one'), which is better than nothing. But there is no explicit contrast with alternatives (update_contact, unlock_field, list_fields) and no stated prerequisite such as an existing guessed field being required for the locking mode.

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