Format a file using the language server's formatter and write the formatted result to disk.
Format a file using the language server's formatter and write the result to disk.
| Name | Required | Description | Default |
|---|---|---|---|
| file | Yes | Relative file path from project root | |
| tabSize | No | Spaces per indentation level (default 2) | |
| insertSpaces | No | Indent with spaces instead of tabs (default true) |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of behavioral disclosure. It does disclose the key side effect: writing the formatted result to disk. However, it does not specify whether the existing file is overwritten, what happens if the language server formatter fails, or any permission requirements, leaving meaningful gaps for a mutating operation.
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 single efficient sentence with no filler. It front-loads the core action ('Format a file') and immediately clarifies the important side effect, making it easy for an agent to scan and understand.
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 relatively simple tool with a fully documented schema, the description covers the essential invocation details and explicitly states the file-modifying behavior. The only notable omissions are usage alternatives and error/overwrite semantics, which prevent a perfect score.
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 100%, so all three parameters (file, tabSize, insertSpaces) are already documented in the input schema. The description adds no additional parameter semantics, which aligns with the baseline 3 for complete schema coverage.
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 uses a specific verb ('Format'), names the exact resource ('a file'), and specifies the mechanism ('the language server's formatter'). It also states the side effect ('write the result to disk'), which clearly separates it from read-only LSP sibling tools like hover or document_symbols.
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 no explicit guidance on when to use this tool versus alternatives. It does not mention related file-modifying siblings such as ts_organize_imports, nor does it state when formatting is appropriate or inappropriate. Usage context is only implied by the tool's name and purpose.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.