Join two Excel sheets using SQL-like join keys (left, right, inner, outer). Specify columns to return and row limit for efficient data merging.
关联两个工作表（类似 SQL JOIN），只回传前 limit 行结果。
参数：
on：关联键列名（两表都要有）
how：left / right / inner / outer（默认 left）
columns：只返回这些列（省 token），省略返回全部
limit：返回行数上限（默认 20）
| Name | Required | Description | Default |
|---|---|---|---|
| on | Yes | ||
| how | No | left | |
| limit | No | ||
| columns | No | ||
| file_path | Yes | ||
| left_sheet | Yes | ||
| right_sheet | Yes |
Changes observed during successful MCP inspections.
v0.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden and does a good job: it discloses the row limit behavior, the column projection behavior, and the default join type. The phrase '只回传' implies a read-only result-returning operation, though it does not explicitly state that no file mutations occur.
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 compact and well-structured: one sentence summarizes the core behavior, followed by a clean bullet list of parameter semantics. Every line adds value and nothing is redundant 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?
For a 7-parameter tool with no output schema and no annotations, the description covers the essential behavioral and parameter details. It could be more complete by explicitly describing the three file/sheet parameters and any edge-case behavior, but the current content is sufficient for an agent to invoke the tool correctly in most cases.
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 0%, so the description must explain the parameters. It does this well for `on`, `how`, `columns`, and `limit`, adding meaning about key requirements, defaults, and token-saving intent. The three location parameters (`file_path`, `left_sheet`, `right_sheet`) are left to inference, but their names make the meaning obvious.
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 a specific operation: joining two sheets like an SQL JOIN and returning only the first `limit` rows. This distinguishes it from sibling tools such as `compare_sheets` and `filter_count` by using the SQL JOIN framing, so an agent can immediately tell what this tool does.
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 the tool: when two sheets need to be correlated via a key column. However, it does not explicitly name alternatives or state when not to use it, so it stops short of a 5.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.