cygnus-ssh-mcp

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ssh_file_delete_line_by_content

Delete one exact line from a remote file over SSH by matching its full content. Fails safely if the line is missing or not unique.

Instructions

Delete a line by its exact content. match_line must match EXACTLY ONE line in the file (whitespace-trimmed, literal text - not a pattern); if it matches zero lines or more than one, the operation fails with a descriptive error rather than guessing which line(s) to delete. Use ssh_file_find_lines_with_pattern first if you're not sure the line is unique. (Equivalent to ssh_file_replace_line_multi(new_lines=[]), provided as a clearer-named shortcut.)

Returns: On success: {'success': True} (no count field - only ever deletes the one matched line). On failure (match not found, match not unique, file not found/unreadable): {'success': False, 'error': str} - not a raised exception.

Long-running calls: if this takes longer than the server's wait cap (default 50s), it
returns {"status": "in_progress", "handle_id": ...} instead of the result - the work keeps
running. Get the result by polling ssh_cmd_check_status(handle_id=...), which returns this
tool's normal response once finished. Do not call it again meanwhile. Only one such
operation runs at a time; another one started meanwhile fails with a 'busy' error.

Input Schema

TableJSON Schema

Name	Required	Description
`force`	No	No longer needed (kept for compatibility): with use_sudo=true the file is read with sudo when the user can't read it. If it can't be read at all, the edit fails - it never reports success without having seen the file.
`use_sudo`	No	Use sudo for the operation
`file_path`	Yes	Path to the file to modify
`match_line`	Yes	Exact line content to match and delete

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv1.6.1Oct 5, 2026

changedInput schema / properties / force / description

Previous value: -"Force operation even if file can't be read (sudo only)"New value: +"No longer needed (kept for compatibility): with use_sudo=true the file is read with sudo when the user can't read it. If it can't be read at all, the edit fails - it never reports success without having seen the file."

First observedv1.3.0May 28, 2026

TDQS

A4.8/5.0

Behavior5/5

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

With no annotations, the description carries the full burden and does so thoroughly: uniqueness constraint, zero/multi-match failure behavior, error returned as a value rather than a raised exception, sudo read semantics, the 50s wait cap with {'status': 'in_progress', 'handle_id'} fallback, the single-concurrent-operation 'busy' error, and the polling tool. This is far beyond what the schema conveys.

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-loads the core action and the uniqueness rule, then uses labeled sections for Returns and Long-running calls. It is longer than typical, but the structure is clear and each block (error contract, wait-cap behavior) carries distinct information, so little is wasted.

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?

For a mutation tool with sudo options and long-running support, the description covers failure modes, return shape, concurrency limits, and async polling. Despite an output schema existing, the extra detail on the non-obvious in_progress/busy behavior leaves nothing an agent needs missing.

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%, so the baseline is 3, but the description adds real semantics: match_line is 'whitespace-trimmed, literal text - not a pattern' and must match exactly one line. It also explains the deprecated force/use_sudo read behavior. Meaningful value over the schema's one-line parameter descriptions.

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?

States a specific verb and resource ('Delete a line by its exact content') and pins down the matching semantics precisely. It distinguishes itself from ssh_file_replace_line by naming the equivalence and from ssh_file_find_lines_with_pattern by pointing to it as a prerequisite. An agent can select it without opening any 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?

Explicitly says to run ssh_file_find_lines_with_pattern first if uniqueness is uncertain, and explains what happens when the match is not unique. It also clarifies this is a shortcut for ssh_file_replace_line_multi(new_lines=[]), giving a clear alternative and the condition that selects each.

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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