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linear_updateIssueCustomField

Idempotent

Set or clear a custom field value on a Linear issue. Pass the issue ID, custom field ID, and value (null to clear).

Instructions

Set or clear a custom field value on an issue. Pass null as value to clear it.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
valueYesJSON-compatible value to write. Use null to clear the field. Arrays and objects are passed through as-is when the Linear schema accepts them.
issueIdYesID or identifier of the issue whose custom field should be updated
customFieldIdYesID of the custom field definition to update

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
rawNo
valueNo
issueIdNo
successNo
currentValueNo
customFieldIdNo
Behavior4/5

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

Description adds the critical behavior of null meaning clear, which is not captured by annotations (idempotentHint, destructiveHint). Annotations already indicate it's safe and idempotent, so the description complements them well.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short, front-loaded sentences with no unnecessary words. The essential information is immediately accessible.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With output schema and annotations providing safety context, the description is sufficient for an update tool. It explains both setting and clearing, which covers common use cases.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with detailed descriptions for each parameter. The description reinforces the null clearing behavior, but adds little beyond the schema. Baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states the tool sets or clears a custom field value on an issue. Distinguishes from general issue update tools like linear_updateIssue by specifying custom fields, but does not explicitly differentiate from siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides a clear usage tip about passing null to clear the field, but offers no guidance on when to use this tool versus alternatives (e.g., linear_updateIssue for standard fields) or any prerequisites.

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

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