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Jev content screen

jev_screen
Read-onlyIdempotent

Screen fetched or pasted text for prompt-injection probability, substance, and relevance to your purpose, then get a pass, review, block, or skip recommendation before the agent reads untrusted content.

Instructions

Judge fetched or pasted text before the agent reads it: prompt-injection probability, substance, and optional relevance to purpose. Recommendation: pass|review|block|skip. Use on untrusted web pages, issues, and pastes. Not for first-party repo files.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
textYesFetched or pasted text before the agent reads it
modelNo
purposeNoWhat the agent is trying to do; enables relevance and skip
block_atNo
review_atNo

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.2.0

TDQS

A4.1/5.0
Behavior4/5

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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false. The description adds behavioral context by explaining what the tool evaluates (injection, substance, relevance) and the output recommendation. It does not contradict annotations and provides useful operational detail beyond the safety profile.

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 two concise sentences. The first sentence states the main function and output, the second gives usage scope. It is front-loaded with the core purpose and contains no fluff. Every sentence earns its place.

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?

The tool has 5 parameters and no output schema, so the description must explain the expected return and any thresholds. It mentions the recommendation output but not the full output structure (e.g., whether it includes probability or substance scores). It also does not explain block_at and review_at parameters, which are essential for controlling the screening behavior. Given these gaps, the description is not fully complete for an agent to call it correctly without additional context.

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 only 40% (text and purpose have descriptions, while model, block_at, and review_at do not). The description mentions 'fetched or pasted text' (text) and 'optional relevance to purpose' (purpose), adding some meaning. However, it does not explain block_at and review_at, which likely set thresholds for the recommendation. Since coverage is low, the description should compensate more, but it only partially does.

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 function: to judge fetched or pasted text for prompt-injection probability, substance, and optional relevance to purpose, and to produce a recommendation (pass|review|block|skip). It explicitly scopes usage to untrusted web pages, issues, and pastes, and excludes first-party repo files, which distinguishes it from sibling tools. The purpose is unambiguous and specific.

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

Usage Guidelines4/5

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

The description provides explicit usage context: 'Use on untrusted web pages, issues, and pastes. Not for first-party repo files.' This tells the agent when to use the tool and when not to. It does not name alternative siblings directly, but the exclusion for repo files implies a different tool is appropriate for that case, which is adequate guidance.

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