Skip to main content
Glama
CaptainCrouton89

MCP Server Boilerplate

json_extract

Extract specific data from JSON files using paths, filters, patterns, or slices to retrieve targeted values, transform data, and analyze specific elements.

Instructions

Extract specific data using paths, filters, patterns, or slices from JSON files. Always use this tool when you need to retrieve particular values, filter arrays/objects by conditions, search for patterns, or slice data. Ideal for targeted data extraction, data transformation, and focused analysis of specific JSON elements.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
file_pathYesPath to the JSON file
pathNoDot notation path to target
filterNoJS condition to filter results (e.g., 'item.age > 18')
patternNoRegex pattern to search for
search_typeNoWhat to search when using pattern
startNoArray slice start index
endNoArray slice end index
keysNoSpecific object keys to extract
default_valueNoFallback if path not found
Behavior3/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It describes the tool's capabilities (extraction methods) but lacks details on error handling, performance characteristics, or output format. The phrase 'Always use this tool when...' is somewhat prescriptive but doesn't contradict any 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?

The description is well-structured and front-loaded with the core purpose. Both sentences earn their place by explaining capabilities and usage guidance. It could be slightly more concise by combining some concepts, but overall it's efficient and clear.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with 9 parameters, no annotations, and no output schema, the description provides adequate context about what the tool does and when to use it. However, it lacks details about return values, error conditions, or behavioral constraints that would be important for a complex extraction tool. The high schema coverage helps compensate somewhat.

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?

The schema description coverage is 100%, so the schema already documents all 9 parameters thoroughly. The description adds value by explaining the overall extraction approach and use cases, but doesn't provide additional parameter-specific semantics beyond what's in the schema. This meets the baseline for high schema coverage.

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 clearly states the tool's purpose with specific verbs ('extract', 'retrieve', 'filter', 'search', 'slice') and resources ('JSON files', 'JSON elements'). It distinguishes from the sibling tool 'json_read' by emphasizing targeted extraction rather than general reading.

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 provides explicit guidance on when to use this tool ('when you need to retrieve particular values, filter arrays/objects by conditions, search for patterns, or slice data') and ideal use cases ('targeted data extraction, data transformation, focused analysis'). It implicitly suggests alternatives by highlighting its specialized nature versus the likely more general 'json_read'.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Install Server

Other Tools

Latest Blog Posts

MCP directory API

We provide all the information about MCP servers via our MCP API.

curl -X GET 'https://glama.ai/api/mcp/v1/servers/CaptainCrouton89/json-mcp'

If you have feedback or need assistance with the MCP directory API, please join our Discord server