Encryptor MCP

append_file

Add text to the end of an existing text file in an unlocked Cryptomator vault while preserving prior contents and creating an undoable logged version.

Instructions

Add text to the end of an existing text file in an open vault that may be changed, exactly as given (start it with a line break to begin a new line). Unlike write_file it needs no version and keeps what's there; to create a file, use write_file. The previous contents are kept as a version and the change is logged, so undo can take it back while the file is unchanged since. Returns the file's new version and the change id; fails if the file doesn't exist or the text is over 5,000,000 characters.

Input Schema

TableJSON Schema

Name	Required	Description
`path`	Yes	A path inside the vault, from its top, for example 'Taxes/2025/receipts.md'.
`vault`	Yes	The vault's name, as listed by the vaults tool, for example 'Taxes'.
`content`	Yes	The text to add to the end of the file, exactly as given. Start it with a line break to add a new line.
`purpose`	Yes	A few words on why, shown to the user or kept in the vault's change log.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedv0.1.4Oct 21, 2026

addedInput schema / properties / content / description

Added value: +"The text to add to the end of the file, exactly as given. Start it with a line break to add a new line."

addedInput schema / properties / path / description

Added value: +"A path inside the vault, from its top, for example 'Taxes/2025/receipts.md'."

addedInput schema / properties / purpose / description

Added value: +"A few words on why, shown to the user or kept in the vault's change log."

addedInput schema / properties / vault / description

Added value: +"The vault's name, as listed by the vaults tool, for example 'Taxes'."

First observedv0.1.3Oct 20, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Annotations only cover safety flags (readOnly=false, destructive=false, idempotent=false), while the description adds the behavior that matters: previous contents are preserved as a version, the change is logged, undo can revert while the file is unchanged since, the 5,000,000-character cap, and the return payload (new version + change id). That is meaningful context beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action, then the write_file contrast, then side effects and return value. Dense and mostly waste-free, though the line-break tip is repeated from the schema.

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?

Even though an output schema exists, the description documents side effects (logging, versioning, undo), failure modes, and size limits, so an agent has everything needed to call and reason about the result.

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

Parameters3/5

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

Schema description coverage is 100%, so all four parameters are already documented in the schema; the description's note to start content with a line break duplicates the schema's own wording. Baseline 3 is appropriate since the description adds no new per-parameter semantics.

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 states a precise verb and resource ('Add text to the end of an existing text file') and immediately contrasts it with the sibling write_file, so an agent can distinguish append-from-create without opening either schema.

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

Usage Guidelines5/5

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

It gives explicit routing: use this to append, use write_file to create, and this tool needs no version. It also states the failure condition (file must already exist), which is exactly the when-not guidance an agent needs.

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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