processInstance_setVariable

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

With no annotations provided, the description carries the full disclosure burden. It adds valuable behavioral constraints: the instance must be 'active' (implying suspension/completion restrictions) and that the operation overwrites existing values. However, it omits other critical mutation behaviors such as error handling for non-existent instances, type validation consequences, or transactional atomicity.

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 description consists of three tightly constructed sentences with no redundancy. It follows an optimal structure: primary action declaration first, required inputs second, and behavioral warning (overwrite) third. Every sentence earns its place.

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 the absence of an output schema, empty input schema, and zero annotations, the description provides minimum viable coverage for a mutation tool. It explains the variable-setting operation but fails to document how to specify the target process instance (a critical parameter for this operation type), leaving a significant documentation 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?

The input schema is empty (0 parameters), establishing a baseline of 4. The description adds essential semantic meaning by explicitly stating the logical parameters required: 'variable name, value, and type'. This compensates for the empty schema. It would achieve a 5 if it also documented the process instance identifier parameter implied by the target resource.

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 description clearly states the specific action ('Set'), the resource ('single named variable'), and the target ('active process instance'). It effectively distinguishes from the sibling tool 'processInstance_setVariables' (plural) by emphasizing 'single', and from 'processInstance_getVariable' by using the verb 'Set'.

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 provides behavioral guidance by stating it 'Overwrites any existing value', which informs the user of the destructive/upsert nature. However, it lacks explicit guidance on when to use this singular setter versus the plural 'setVariables', or prerequisite conditions like requiring the process instance ID.

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