ActionGuard Protocol Inspector Agent
Server Details
Diff and poisoning detection for MCP servers: catch schema drift and prompt poisoning.
- Status
- Healthy
- Last Tested
- Transport
- Streamable HTTP · MCP 2024-11-05
- URL
- Repository
- lsendel/actionguard
- GitHub Stars
- 0
TDQS
Scored across 2 tools
check_drift targets a specific pinned-hash comparison, while inspect runs a broader multi-stage audit. The overlap is limited to schema evaluation, but an agent might still wonder whether inspect includes drift detection, causing minor ambiguity.
Both tools share the actionguard_ prefix and use snake_case, but check_drift follows a verb_noun pattern while inspect is a bare verb, creating a minor inconsistency.
Two tools is on the low side for a protocol inspector; while each has a clear purpose, the surface feels thin and could benefit from additional operations like baseline management or report retrieval.
The server lacks any tool to set or update the pinned Dual-Hash required by check_drift, leaving a dead end. Core inspection tasks are covered, but baseline lifecycle and result retrieval are missing.
Available Tools
2 toolsactionguard_check_driftBRead-onlyInspect
Verify whether an MCP server's tools schema or descriptions have drifted from a pinned Dual-Hash.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | The target MCP server endpoint URL | |
| pinnedSchemaHash | Yes | Pinned 64-char hex SHA-256 schema hash |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The readOnlyHint=true annotation already establishes that this is a non-mutating check, so the description only needs to add context. It does convey that both schemas and descriptions are compared against a pinned value, but it never explains what 'Dual-Hash' means, whether a mismatch is returned as a boolean/verdict, or how the two hashes differ.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single front-loaded sentence with no filler; the verb and object lead immediately. The only cost is the unexplained 'Dual-Hash' term, which spends words without fully informing the reader.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a two-parameter read-only check with no output schema, the description covers the what but not the outcome: it does not say whether the result is a pass/fail verdict, a diff, or which of schema vs. description drifted. With annotations covering safety, this is adequate but leaves a real gap in interpreting the result.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100% for both parameters, so url and pinnedSchemaHash are already fully documented as endpoint and 64-char hex SHA-256 hash. The description's mention of a 'pinned Dual-Hash' loosely reinforces pinnedSchemaHash but adds no format, sourcing, or acquisition detail beyond the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb (Verify) and resource (an MCP server's tools schema or descriptions) plus the comparison basis (a pinned Dual-Hash), so the operation is unambiguous. It does not, however, distinguish itself from the sibling actionguard_inspect, leaving the boundary between 'check drift' and 'inspect' to inference.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
There is no explicit when-to-use or when-not-to-use guidance, and the only sibling, actionguard_inspect, is never mentioned even though it is the obvious alternative for examining a server. The agent must guess whether drift checking is a pre-flight step, a post-deploy audit, or a substitute for inspection.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
actionguard_inspectBRead-onlyInspect
Run a 5-stage continuous reliability, security, and schema audit of an MCP server or AI agent endpoint.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | The target MCP server or agent endpoint URL to audit |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The readOnlyHint=true annotation already establishes the safety profile, and the description is consistent with it. It adds the useful detail that the audit covers five stages across reliability, security, and schema, but omits execution characteristics an agent would want: whether the scan is synchronous or long-running, what the response contains, and any rate limits or auth requirements.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single front-loaded sentence with no filler; the verb, scope, and target all land in the first clause. Nothing could be cut without losing information.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
There is no output schema, so the description carries the burden of telling the agent what comes back from a five-stage audit, and it does not. For a tool this complex with a sibling that overlaps in domain, the definition is minimally viable rather than complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100% for the single 'url' parameter, so the schema already documents it fully. The description adds nothing about URL form (MCP SSE endpoint vs. agent HTTP endpoint) beyond restating the target, which is the expected baseline when the schema does the work.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
Specific verb ('Run') plus resource ('MCP server or AI agent endpoint') and a named scope ('5-stage continuous reliability, security, and schema audit'), so the agent knows exactly what class of operation this is. It does not, however, distinguish itself from the sibling actionguard_check_drift, which is a closely related audit verb.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No when-to-use, when-not-to-use, or alternative routing is given. The word 'continuous' hints at repeated/scheduled invocation, but the description never states when an agent should pick this over actionguard_check_drift or what prerequisites (auth, reachability) must hold.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
2 tool updates
- First observed
actionguard_check_drift - First observed
actionguard_inspect
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