fuzzy_merge

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

With no annotations, the description carries the behavioral disclosure burden. It discloses that the tool appends Table.FuzzyNestedJoin and optionally Table.ExpandTableColumn to the table's M query, which is a key side effect. It also explains joinKind and threshold semantics, adding context beyond the schema.

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 is a dense, well-organized paragraph of about 60 words. Every sentence contributes: purpose, behavior, key parameter formats, join types, threshold, and transformationTable. It is front-loaded with the tool's purpose and avoids redundancy with the schema.

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 tool's complexity (12 parameters) and lack of an output schema, the description covers the core operation, key parameters, and side effects. It does not explain return values, but the M query modification is clearly the primary outcome. The description is sufficient for an agent to understand the tool's role and main requirements.

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 coverage is 83%, giving a baseline of 3. The description adds significant value by specifying that leftKeys/rightKeys are 'comma-separated equal-length lists', defining threshold as a 0..1 similarity cut-off, and clarifying transformationTable as a {From,To} mapping query name. These details go beyond the basic schema descriptions.

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 tool 'joins another query on APPROXIMATE key matches' with specifics (typos, casing, spacing), making it distinct from exact-match merge tools. It identifies the resource as a Power Query merge operation and specifies the M query steps appended.

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 gives clear context for when to use this tool: when approximate matches are needed rather than exact joins. It does not explicitly list exclusions or alternatives, but the fuzzy matching context differentiates it from standard merge_queries and related sibling tools.

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