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furl_compress

Compress large tool outputs, file contents, or logs to reduce context usage, with a retrieval hash to restore the original whenever needed.

Instructions

Compress content to save context window space. Use this on large tool outputs, file contents, search results, or any content you want to shrink before reasoning over it. Pass 'content' with inline text, OR 'file_path' to have the server read and compress a file from disk (ideal for a large trace/log that would overflow context if pasted inline) — exactly one of the two. When it compresses, the original is stored and can be retrieved later via mcp__furl__furl_retrieve: returns compressed text + a hash for retrieval. When Furl decides NOT to compress (a no-op: the content is too small or would not shrink) it returns the original unchanged with hash null and stores NOTHING, so a no-op does not consume a retrieval slot — pass persist=true to store it anyway and get a hash back. Optional 'mode' controls aggressiveness; optional include/exclude patterns limit which lines are compressed.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
modeNoCompression aggressiveness (default 'normal' = current behavior). 'lossless_only': only proven-lossless transforms run — nothing is dropped or substituted, so the output carries no retrieval markers (larger, fully reversible). 'aggressive': keep fewer items per crush and accept marginal compressions the default would reject (smaller output; all drops stay CCR-recoverable).
contentNoThe inline content to compress. Any text: tool output, JSON, search results, logs, code, etc. Provide EITHER content OR file_path, not both.
persistNoStore the original even when compression is a no-op (default false). When Furl decides not to compress because the content is too small or would not shrink, it returns the original unchanged and, by default, does NOT store it, so a no-op no longer consumes a retrieval slot. Set true to store it anyway and get a retrieval hash back.
file_pathNoAbsolute path to a file the server reads from disk and compresses, so a large artifact (e.g. a multi-MB trace or log) never has to be pasted inline and pay the full context cost first. Confined to the workspace. Provide EITHER file_path OR content, not both. Larger byte ceiling than inline content (override with FURL_MCP_MAX_FILE_BYTES).
exclude_patternsNoGlob-or-regex patterns. Any content line matching one is PROTECTED — passed through verbatim, never compressed. Applied on top of include_patterns.
include_patternsNoGlob-or-regex patterns (regex tried first, glob fallback). When set, ONLY content lines matching at least one pattern are eligible for compression; all other lines pass through verbatim.
Behavior5/5

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

With no annotations provided, the description carries the full burden. It transparently discloses key behavioral traits: the original is stored and retrievable via furl_retrieve, a no-op returns original unchanged with hash null and stores nothing, persist=true overrides this, mode controls aggressiveness, and include/exclude patterns gate which lines compress. This is far beyond minimal disclosure.

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

Conciseness5/5

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

The description is information-dense without fluff. It front-loads the core purpose, then methodically covers usage modes, side effects, and parameters. Every sentence contributes value, and the use of dashes to separate clauses improves readability without losing precision.

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?

Given no output schema, the description adequately explains return behavior: compressed text plus a hash for retrieval, and original unchanged with hash null for no-op. It also covers disk file reading, pattern restrictions, and persistence. The tool's complexity is high, but the description leaves no major functional gap for an agent to select and invoke it correctly.

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

Parameters5/5

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

Even though schema coverage is 100%, the description adds significant meaning beyond the schema. It explains the 'exactly one of the two' constraint for content/file_path, clarifies the consequence of persist=true in no-op scenarios, and contextualizes mode and pattern parameters. This transforms raw parameter listings into functional understanding.

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 opens with a specific verb and resource: 'Compress content to save context window space.' It clearly distinguishes from sibling tools (furl_retrieve, furl_search, etc.) by focusing on the compression operation. The scope of when to use it (large tool outputs, file contents, search results) further clarifies its purpose.

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?

The description explicitly states when to use the tool: 'Use this on large tool outputs, file contents, search results, or any content you want to shrink before reasoning over it.' It also explains the alternative path via mcp__furl__furl_retrieve for retrieving compressed content. The mutual exclusivity of 'content' and 'file_path' is clearly spelled out, along with the persists=true option for no-op cases, providing thorough usage guidance.

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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