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Coalesce-Software-Inc

coalesce-transform-mcp

Official

Apply Join Condition

apply_join_condition
Idempotent

Writes JOIN conditions for nodes with multiple predecessors by detecting common columns, supporting custom join types, WHERE, and column overrides.

Instructions

Write a FROM/JOIN/ON clause to a workspace node's sourceMapping.join.joinCondition by analyzing predecessor columns and generating the join automatically.

Use this for multi-predecessor nodes where you need to combine data via JOIN. The tool inspects predecessor columns, finds common column names for ON conditions, and writes the full joinCondition to the node.

Args:

  • workspaceID (string, required): The workspace ID

  • nodeID (string, required): The node ID of the multi-predecessor node

  • joinType (enum, optional): 'INNER JOIN' | 'LEFT JOIN' | 'RIGHT JOIN' | 'FULL OUTER JOIN'. Defaults to INNER JOIN

  • whereClause (string, optional): WHERE filter to append after the JOIN (without the WHERE keyword)

  • qualifyClause (string, optional): QUALIFY clause to append (without the QUALIFY keyword)

  • joinColumnOverrides (array, optional): Explicit column mappings when column names differ across predecessors. Each entry: { leftPredecessor, rightPredecessor, leftColumn, rightColumn }

Returns: { nodeID, joinCondition, warning?, validation? }

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
nodeIDYesThe node ID of the multi-predecessor node
joinTypeNoType of JOIN to use between predecessors. Defaults to INNER JOIN.
whereClauseNoOptional WHERE clause to append after the JOIN (without the WHERE keyword).
workspaceIDYesThe workspace ID
qualifyClauseNoOptional QUALIFY clause to append (without the QUALIFY keyword).
joinColumnOverridesNoExplicit column mappings for joins when column names differ across predecessors. Overrides auto-detected common columns for the specified predecessor pair.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
nodeIDNo
createdNo
warningNo
nextStepsNo
validationNo
joinSuggestionsNo
configCompletionNo
nodeTypeValidationNo
configCompletionSkippedNo
Behavior4/5

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

Annotations indicate write, idempotent, and non-destructive behavior. The description adds that it writes to sourceMapping.join.joinCondition, inspects columns, and auto-generates conditions. This complements the annotations without contradiction. It could mention overwriting behavior, but overall high transparency.

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?

The description is well-structured: a purpose sentence, usage guidance, then bullet lists for args and returns. No unnecessary words, each sentence contributes. It is front-loaded with the key action.

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

Completeness5/5

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

Given 6 parameters, a described output object, and annotations, the description covers all aspects: what it does, when to use, inputs, outputs, and behavior. No gaps remain for an agent to misuse the tool.

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

Parameters4/5

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

Schema coverage is 100%, providing baseline 3. The description adds meaning beyond schema: explains purpose of each param, defaults for joinType, and clarifies joinColumnOverrides usage for mismatched column names. This adds significant value.

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

Purpose5/5

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

The description clearly states the tool writes a FROM/JOIN/ON clause to a specific node property by analyzing predecessor columns and generating join conditions automatically. It uses a specific verb and resource, distinguishing it from sibling tools like convert_join_to_aggregation.

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

Usage Guidelines4/5

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

The description explicitly says to use for multi-predecessor nodes needing JOINs, and explains the automatic column matching. It does not mention exclusions or alternatives, but the context is clear and sufficient for selecting this tool.

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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