vsp360-mcp
Provides access to the Hitachi VSP 360 1.4 REST API, enabling interaction with VSP 360 storage operations across areas such as device registry, platform alerts, cluster health, and analytics queries.
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@vsp360-mcpshow me volumes that have no host path"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
vsp360-mcp: Community MCP server for Hitachi VSP 360
An MCP server for the Hitachi VSP 360 1.4 REST API, built from the Platform OpenAPI spec spec/Platform-vsp360-openapi.yaml. It gives Claude (or any other MCP client) access to all 264 API operations. The token endpoint is excluded because the server handles authentication itself.
Not an official Hitachi Vantara product: vsp360-mcp is an independent, community project, and isn't supported by or affiliated with Hitachi Vantara. Hitachi and VSP 360 are trademarks of their owners.
How it exposes the API
The spec is too large to load as 264 separate tools: their schemas alone come to about 400 KB. The server therefore always provides three discovery tools:
Tool | Purpose |
| Lists the 35 API areas. With |
| Shows the parameters, request body, response schema, required permissions and prerequisites for one operation. |
| Calls any operation by |
For the areas you use most, set VSP360_TOOLSETS to add direct tools: one tool per operation, each with a full input schema. For example:
VSP360_TOOLSETS="Device Registry,Platform Alerts,VSP 360 Cluster Health"How vsp360_list_operations finds operations
A search goes through three steps. Only the first one ranks; the other two add advice to the ranked list.
BM25 ranking picks and orders the operations.
A confidence rating (HIGH, MEDIUM or LOW) says how far to trust the top result.
An optional learned hint suggests what to do next. It is off unless
VSP360_DECISION_HINTis set.
1. BM25 ranking
A query is ranked with BM25 over each operation's ID, summary, tag, path, description and a set of example questions (spec/examples.json), so plain-language requests work ("volumes with no host path", "silence alerts"). The ranking has six refinements:
Fields are weighted: words in the summary and ID count more than words in the description.
camelCase is split and light stemming is applied.
Storage vocabulary is mapped to API terms, for example volume → ldev, LDAP → directories, ESXi → hypervisor.
Verbs decide intent: "list" and "show" favour read operations, while "delete", "start" and "register" favour write operations.
List-style requests prefer collection endpoints over
{id}endpoints.Example questions bridge operator wording and API wording: each operation has a few questions an operator might ask, such as "take a snapshot now outside the schedule" for
protectionTriggerPolicy. SetVSP360_EXAMPLESto another file to use your own, or to an empty string to turn them off.
2. Confidence rating
Each result set carries a confidence of HIGH, MEDIUM or LOW, based on how far the top hit leads the next and how much of the request's own wording it matches. The rating comes with advice: call the top result, check its description, or describe the top two or three. With HIGH confidence, the top result's parameters are listed too (types, enum values, required body fields), so Claude can usually call it without spending a turn on vsp360_describe_operation. This is skipped when the top result is blocked by the current settings, and for analyticsRunQuery, which needs describe's MQL reference. When a LOW or MEDIUM result looks like a performance or topology question, the response points to analyticsRunQuery.
3. Learned hint (optional)
With VSP360_DECISION_HINT=true, a line under the results suggests what to do with them: call the top operation, compare the top few, answer with Analytics, or search again. It comes from a small model in spec/decision-model.json, trained on logged searches (see Improving search). It never changes the ranking. With ab, it is shown in a random half of server sessions so the two can be compared.
Analytics (MQL) field reference
The spec documents the Analytics query endpoint but not what it can query. Describing analyticsRunQuery therefore adds an mqlReference: MQL usage notes, the attributes and relations of the most-used resource types (raidStorage, raidPool, raidLdev, raidPort, raidHG, raidLU, raidPortWWN, raidPair, the host, fabric and VMware types), and the names of the other 38 types. Describing it with resourceType (for example raidPool) returns one type's full attribute list. The block, file and object types come from the VSP 360 Metrics Reference Guide; the host, fabric and VMware types were found on a live system and may be incomplete. The reference lives in spec/analytics-fields.json (VSP360_ANALYTICS_FIELDS points to another file).
Measuring search
All user questions live in tests/user-queries.md: regression prompts, labelled questions for evaluation and training, and batch questions for data collection.
npm test builds the server, runs the unit tests in tests/unit/ (the HTTP client against a mock server, the spec loader, and the MCP server end to end, including the read-only block) and then the search evaluation, which fails if any score drops below its threshold. npm run eval scores the search against 83 labelled development requests (45 held out from tuning) and the 119 labelled user questions in tests/user-queries.md (79 held out); EXAMPLES=0 npm run eval measures it without the example questions.
Related MCP server: wasabi-wacm-connect-mcp
Safety: read-only by default
By default only GET operations are allowed, plus a few POST operations that only query or validate:
analytics query (only with
action=query)inventory filter query
authorization check
user capabilities
CSV validation
upgrade version validation
All other operations are refused, and direct tools are not created for them. These include device registration and deletion, the directory connection test (it makes VSP 360 connect to whatever LDAP host it's given), orchestration workflows (volume allocation, expansion, GAD), user and group changes, certificates, upgrades and notifications. To allow them, set VSP360_ALLOW_WRITES=true. DELETE tools are marked destructiveHint, so Claude asks for confirmation before running them.
Operations that return secrets. Three operations return a live client secret, which would then become part of the conversation: the read vsp360GetServiceAccountSecret, and the writes vsp360RevealBlockSSOSetup and vsp360RotateBlockSSOSecret, which return a block storage SSO client secret. Every other operation masks secrets. These three are refused, whether or not writes are allowed, unless VSP360_ALLOW_SECRET_READS=true.
Connections. VSP360_URL must be https:// unless VSP360_ALLOW_HTTP=true. The token request never follows a redirect, and API requests follow redirects only within VSP360_URL, so the client secret and access token aren't sent anywhere else.
Local files. Claude chooses save_to and upload paths, so text it reads from the API could try to steer them. save_to therefore only writes inside VSP360_DOWNLOAD_DIR, checked with symlinks resolved, never into a hidden folder such as ~/.ssh, and never over an existing file (set VSP360_SAVE_ANYWHERE=true to lift the folder rule). Uploads refuse hidden files and folders such as ~/.ssh or .env; set VSP360_UPLOAD_DIR to allow uploads only from one folder. In read-only mode, the one upload allowed (CSV validation) is refused unless VSP360_UPLOAD_DIR is set, because it would otherwise let a steered model send any local file to VSP 360.
Features
Auth: Gets an OAuth2
client_credentialstoken fromPOST /api/v1/vsp360/auth/token. It reuses the token until shortly before it expires and fetches a new one automatically after a 401.Pagination: Use
limitandoffset(at most 100 per page), or setall_pages: trueto fetch every page. When the first page'sLinkheader gives bothnextandlast, the remaining pages are fetched four at a time; otherwise thenextlinks are followed one by one.max_pagescaps the number of pages; it defaults to 20, and at most 200 are fetched. TheContent-RangeandLinkheaders are included in each result. If a later page is not JSON (for example a gateway error page), the pages before it are kept and a note says where it stopped.Downloads: Binary responses are streamed to
VSP360_DOWNLOAD_DIR, so large bundles never sit in memory, and the file path is returned. These include diagnostic bundles (.tar.gz), CSR ZIPs and billing reports. A name the server already used gets a numbered suffix. Any call can also passsave_to: "report.json"(a file name or a path inside the download folder); withall_pages, every page is saved.Uploads: Multipart operations take local file paths, for example
files: {"file": "~/devices.csv"}. This applies to installing a TLS certificate, validating a bulk-registration CSV, and uploading an upgrade package. Files are streamed from disk, so 20 GB.zstupgrade packages don't need to fit in memory. Hidden files are refused (see Safety).TLS: Use
VSP360_CA_CERTfor a private CA. UseVSP360_INSECURE_TLS=trueonly for lab systems with self-signed certificates.Compact responses: JSON responses and
vsp360_describe_operationoutput are returned without indentation, which is about 40% fewer characters for the model to read. Files written withsave_tostay indented.Large responses: Responses longer than
VSP360_MAX_RESPONSE_CHARSare truncated, with a note telling Claude how to narrow the request. A response larger thanVSP360_MAX_RESPONSE_BYTES(64 MiB) isn't read into memory: the call fails and suggestssave_to, which streams the response to a file. Withall_pages, the limit covers all pages together, and the pages before it are kept.
Improving search: logging and the learned hint
These tools collect data on how Claude uses search results and train the learned hint from it. None of them is needed to use the server.
Decision log
Set VSP360_DECISION_LOG to a file path to record, locally, how search results are used:
For each search: the query and, if Claude passes it, the user's own request that led to the search (the
requestargument, offered only while the log is on and never used for ranking); the confidence rating and the signals behind it (lead, coverage, intent, the analytics hint), and the ranked operationIds.For each describe or call: the operationId, its rank in the most recent search if it started within
VSP360_DECISION_LINK_SECONDSof it (otherwise it is logged as unlinked), the seconds since that search, the HTTP status and the duration. Calls also record the names of the arguments used.
Argument values, request and response bodies, headers and credentials are never logged. The query text is logged as typed, so treat the file as you would chat history.
Collection mode
With VSP360_DECISION_COLLECT=true (and the log on), the server makes every question produce a labelled search: a search with query must also carry request, and vsp360_call_operation (or a direct tool) is refused unless the operation appeared in a search result within the last VSP360_DECISION_COLLECT_SECONDS (default 600). Refusals are logged. Claude is slower in this mode, so turn it on for a data-collection period and off afterwards; turning writes off (VSP360_ALLOW_WRITES unset) for the period is also a good idea.
Batch collection
npm run collect-batch -- --part N sends the questions in one part of tests/user-queries.md to Claude through the API, one fresh conversation per question, with its own vsp360 server running read-only in collection mode. It needs an Anthropic API key (ANTHROPIC_API_KEY; usage is billed), skips the held-out test questions, resumes where it stopped, and writes to reports/decisions-batch.jsonl (decisions) and reports/batch-answers.jsonl (answers, which contain live VSP 360 data). --dry-run lists what would run; --limit N, --only 1,2, --model and --effort adjust a run.
Training the learned hint
spec/decision-model.json is a small learned model (npm run train-decision -- --write rebuilds it) that suggests what to do with a search result: call the top operation, compare the top few, use Analytics, or search again. With VSP360_DECISION_HINT=true the suggestion is added under the search results; with ab it is shown in a random half of server sessions, so the decision log can compare sessions with and without it. While the log is on, the prediction is recorded either way. collect-batch takes --hint off|on|ab.
Reports
npm run decision-report -- <log.jsonl> [--csv out.csv] turns the log into one row per search, labelled with what happened next (top result called, another result called, an operation not in the results called, or nothing called). Searches whose request matches a held-out test question in tests/user-queries.md are flagged so they can be kept out of training. When the hint runs in ab mode, the report also compares sessions that saw it with sessions that did not. npm run train-decision trains the model on these rows and compares it with the confidence thresholds on held-out questions.
Setup
INSTALL.md has the full installation and deployment guide, including Windows, CI/CD pipelines, checksums, upgrading and troubleshooting. In short:
First, create a service account in VSP 360 and note its client ID and secret. Give it the access your use case needs: admin covers alerts, logs and system operations; for devices, use a group whose access policy covers the device types.
Then install the server in one of these ways. Each GitHub release has the packages and a SHA256SUMS file.
Package | Needs | Use it for |
| Claude Desktop | One-click install: open the file and Claude Desktop asks for the URL, client ID and secret. |
| Claude Desktop, with the extension | Optional skill for Tufte-style capacity and performance charts. Upload it under Settings → Capabilities → Skills; see INSTALL.md. |
| nothing | Standalone install on macOS, Linux or Windows (x64 and arm64), with Node.js bundled in. |
npm package ( | Node.js 20+ |
|
Docker image | Docker | See README.docker.md. |
Source | Node.js 22+ | Development: |
Standalone. Unpack the archive anywhere and use bin/vsp360-mcp (bin\vsp360-mcp.cmd on Windows) as the server command. You can symlink it onto your PATH:
tar -xzf vsp360-mcp-0.1.26-linux-x64.tar.gz -C /opt && ln -s /opt/vsp360-mcp-0.1.26-linux-x64/bin/vsp360-mcp /usr/local/bin/vsp360-mcpnpm or CI/CD. Install from the npm registry (version 0.1.17 and later). The vsp360-mcp command then starts the server:
npm install -g vsp360-mcpEach GitHub release also has the same package as vsp360-mcp-<version>.tgz, for machines that can't reach the registry.
Claude Code plugin. The plugin/ folder packages the server with capacity, charting and health-check skills: /plugin install vsp360-community --marketplace visubramaniam/vsp360-mcp. See README.plugin.md for installing, configuring and using it.
The examples below use vsp360-mcp as the command; substitute the path from whichever install you chose.
Claude Code
claude mcp add vsp360 -e VSP360_URL=https://vsp360.example.com -e VSP360_CLIENT_ID=my-service-account -e VSP360_CLIENT_SECRET=REPLACE_ME -e "VSP360_TOOLSETS=Device Registry,Platform Alerts" -- vsp360-mcpClaude Desktop
The .mcpb package is the easiest way. To configure it by hand instead, add this to ~/Library/Application Support/Claude/claude_desktop_config.json. Claude Desktop does not read your shell's PATH, so give the command's full path, e.g. /usr/local/bin/vsp360-mcp:
{
"mcpServers": {
"vsp360": {
"command": "/usr/local/bin/vsp360-mcp",
"env": {
"VSP360_URL": "https://vsp360.example.com",
"VSP360_CLIENT_ID": "my-service-account",
"VSP360_CLIENT_SECRET": "REPLACE_ME",
"VSP360_TOOLSETS": "Device Registry,Platform Alerts"
}
}
}
}To try the tools interactively, run npm run inspect. It opens the MCP Inspector and needs the environment variables set in your shell.
Configuration
Variable | Default | Description |
| (required) | Base URL, e.g. |
| (required) | Service account client ID |
| (required) | Service account client secret |
| Optional OAuth scope | |
|
| Allow operations that change state |
|
| Allow the three operations that return a live client secret (see Safety) |
| (none) | Comma-separated API areas (tags) to expose as direct tools. |
| PEM file of the CA that signed the VSP 360 certificate | |
|
| Skip TLS verification (lab use only) |
|
| Allow an |
|
| Request timeout; uploads are exempt |
|
| Truncation limit for text responses |
|
| Most bytes read into memory from one response, or from all pages of an |
|
| Where binary downloads and |
|
| Let |
| (any non-hidden path) | Only allow uploads from inside this folder. In read-only mode, uploads are refused unless it's set. |
|
| Path prefixes to rewrite, as comma-separated |
| bundled | MQL resource types and attributes added to |
| bundled | Example user questions per operation, used to rank search results. Set to an empty string to turn them off. |
| bundled spec | Path to a different OpenAPI file, YAML or JSON, e.g. a newer VSP 360 release. JSON loads faster. |
These settings belong to the optional search-improvement tools (Improving search); none is needed to use the server:
Variable | Default | Description |
| (off) | Path to a JSON Lines file. When set, each search, describe and call is logged locally (see Decision log). |
|
| A describe or call is tied to the latest search only if it starts within this many seconds of it. |
|
|
|
|
| In collection mode, how long a search result keeps its operations callable. |
|
|
|
| bundled | The learned model used by the hint. |
Tag names for VSP360_TOOLSETS
Users · Groups · Group Access · Service Accounts · Roles · Identity Providers · Active Directory · Authentication Settings · Authorization · Access Catalog · Access Policies · Privileged Access Management · Block Single Sign-On · Device Registration · Device Registry · Device Operation Jobs · File and Object Device Registration · Host and Hypervisor Discovery · Platform Alerts · VSP 360 Cluster Health · Logs · Diagnostics · Platform Profiles · Resource Management · Platform Upgrade · Application Lifecycle · TLS Certificates · Trusted CA Certificates · Notifications · Usage and Billing Reports · Product Information · Data Protection / Copies · Data Protection / Policies · Orchestration / Execute Workflows · Analytics / Query API
Building the packages
npm run package builds every release package into release/. Use --only npm,mcpb,standalone,skill and --targets linux-x64,... to build fewer, e.g. npm run package -- --only standalone --targets darwin-arm64. The standalone packages bundle Node.js 24, downloaded from nodejs.org and checked against its published SHA-256 sums. The Claude Desktop extension is packed with npx @anthropic-ai/mcpb@2.1.2, which is downloaded when needed rather than kept as a dev dependency.
The Release workflow runs when a v* tag is pushed. It runs the tests, builds the packages and attaches them to the tag's GitHub release; if that release doesn't exist yet, it's created from the version's CHANGELOG.md section. It then publishes the same .tgz to the npm registry with trusted publishing, so no npm token is stored and each version gets a provenance attestation; this is skipped if that version is already on npm. The trusted publisher is set up on npmjs.com under the package's Settings → Trusted Publisher (repository visubramaniam/vsp360-mcp, workflow release.yml). It pushes the linux/amd64 and linux/arm64 Docker image to ghcr.io/visubramaniam/vsp360-mcp using the workflow's own token, and also to Docker Hub if the DOCKERHUB_USERNAME and DOCKERHUB_TOKEN repository secrets are set. To rebuild an existing tag's packages, run the workflow by hand with that tag.
The Claude plugin in plugin/ installs the server from its own lockfile, so it can only use a version that's already on npm. After a release is published, update it in a follow-up pull request: set the version in plugin/package.json (its version and the vsp360-mcp dependency) and in plugin/.claude-plugin/plugin.json, then run npm install --package-lock-only --ignore-scripts in plugin/ to regenerate package-lock.json. tests/unit/plugin.test.mjs checks that the three agree, that the lockfile meets the directory's rules, and that the plugin isn't ahead of package.json.
Updating for a new VSP 360 release
Replace spec/Platform-vsp360-openapi.yaml (or point VSP360_SPEC at the new file) and restart the server. No code is generated from the spec, so nothing needs rebuilding. npm run build keeps a pre-parsed copy of the bundled spec in dist/openapi-cache.json, so the server starts without parsing YAML. The copy is only used while the YAML file is unchanged, so a replaced file is parsed afresh, which adds about a quarter of a second to startup. Run npm run build again to refresh the copy. If the new release adds POST operations that only read data, add them to READ_ONLY_POSTS in src/spec.ts.
Contributing
Bug reports, search problems, documentation fixes and code are all welcome. CONTRIBUTING.md explains how to set up, test and submit a change, and the rules for keeping live VSP 360 data out of this public repository. Everyone taking part is expected to follow the Code of Conduct. Report security problems privately, as SECURITY.md describes.
License
The code in this repository is released under the MIT License. The VSP 360 OpenAPI definition in spec/ describes Hitachi Vantara's product API and is not covered by this license.
Available Tools
3 toolsvsp360_call_operationARead-only
Call any VSP 360 REST API operation by operationId. Authentication is handled automatically. Pass path, query and header parameters by name in params, and the JSON request body in body. Collections are paginated with limit/offset (max 100 per page); set all_pages to follow the next link. Binary responses (ZIP, gzip, CSV downloads) are saved to the download folder and the file path is returned. Only read operations are allowed; the server runs read-only.
| Name | Required | Description | Default |
|---|---|---|---|
| body | No | Request body (JSON object or array) for POST/PUT/PATCH operations. For multipart uploads, the non-file form fields. | |
| files | No | Multipart uploads only: form field name -> local file path | |
| params | No | Path, query and header parameters by name, e.g. {"id": "123", "limit": 100} | |
| save_to | No | Write the response to this file instead of returning it: a file name, or a path inside the download folder. Existing files are not overwritten. | |
| all_pages | No | Follow RFC 8288 `next` links and return every page (GET collections only). | |
| max_pages | No | Page cap when all_pages is set (default 20). | |
| operationId | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description nonetheless adds substantial non-obvious behavior: automatic authentication, a 100-item per-page pagination ceiling, the RFC 8288 `next` traversal model, and that binary responses (ZIP/gzip/CSV) are written to a download folder with the path returned. Error behavior and rate limits are not mentioned, keeping this short of a 5.
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?
Five tight sentences, all front-loaded with the core call contract first, then auth, then pagination, then output handling. No sentence is redundant with structured fields, and nothing is padded.
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 generic dispatcher with 7 params and no output schema, the description covers the essential calling contract plus return-value handling for binary payloads. The main gap is workflow context: it does not tell the agent to resolve operationId via the sibling list/describe tools, which is the one thing an agent most needs before calling.
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 coverage is already 86%, so the baseline is 3. The description adds meaning beyond the schema by explaining that path/query/header params are passed by name in `params`, that the body is JSON for POST/PUT/PATCH, and that pagination is limit/offset capped at 100 per page with all_pages following the `next` link. This directly clarifies how the loosely-typed `params` object is populated.
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 action and scope: call any VSP 360 REST API operation by operationId, with auth handled automatically. It is clear what the tool does, but it never differentiates itself from its siblings (list_operations, describe_operation), leaving the agent to infer that this is the execution step of a discover-then-call workflow.
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?
Usage is implied rather than stated: pagination guidance is conditional and useful ('all_pages ... GET collections only', max 100 per page), and the read-only constraint is made explicit. However, it gives no guidance on when to use this versus vsp360_list_operations / vsp360_describe_operation, nor how to obtain a valid operationId, which is the required parameter.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
vsp360_describe_operationARead-only
Show everything needed to call one VSP 360 operation: method and path, required permissions and prerequisites, parameters, request body schema and response schema.
| Name | Required | Description | Default |
|---|---|---|---|
| operationId | Yes | operationId from vsp360_list_operations | |
| resourceType | No | analyticsRunQuery only: an MQL resource type (e.g. raidPort, raidPool, vm) to list all its attributes and relations. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuine value by enumerating what the response contains (method/path, permissions, prerequisites, parameters, request and response schemas), which matters because there is no output schema.
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?
One front-loaded sentence with a colon-delimited inventory and no filler. It is tight and readable, though the enumeration is broad rather than prioritized.
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?
With no output schema, the description carries the burden of describing return contents and does so well, and parameters are fully documented in the schema. It stops short of covering error behavior or what happens if permissions/prerequisites are unmet.
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 coverage is 100%, so both parameters are already documented, including the resourceType edge case scoped to analyticsRunQuery. The description contributes only a generic mention of 'parameters' and does not clarify operationId sourcing or the resourceType special case. Baseline 3 is appropriate.
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 (Show) and resource (one VSP 360 operation) plus the scope of returned metadata. It implicitly contrasts with vsp360_call_operation by framing itself as a lookup rather than an invocation, but never names a sibling, so differentiation is inferred rather than explicit.
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?
Usage is only implied: an agent infers this is the inspection step before calling an operation. There is no explicit 'use this when' statement, no exclusions, and the dependency on vsp360_list_operations appears only in the schema's parameter description, not the description text.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
vsp360_list_operationsARead-only
Browse the VSP 360 REST API. With no arguments, lists the API areas (tags) and how many operations each has. With tag and/or query, lists matching operations (operationId, method, path, summary). Use this first to find the operationId you need, then vsp360_describe_operation and vsp360_call_operation. Operations marked [write] are blocked because the server runs read-only.
| Name | Required | Description | Default |
|---|---|---|---|
| tag | No | API area, e.g. 'Device Registry', 'Platform Alerts', 'Users'. Case-insensitive. | |
| limit | No | Maximum results for a query (default 10). | |
| query | No | What you want to do, in plain words (e.g. 'volumes with no host path', 'replication pairs status'). Ranked by BM25 relevance with a confidence rating. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is partly covered. The description adds real context beyond that: write-tagged operations are blocked server-side, and the no-argument invocation switches the tool into a different listing mode. It does not state whether results are truncated or how the confidence rating on query results behaves.
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?
Three tightly packed sentences with zero filler, front-loaded with the no-argument default before the filtered mode and the follow-up workflow. Every clause carries information an agent needs to call the tool correctly.
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, and the description compensates by naming the returned fields (operationId, method, path, summary) for both modes. Combined with the workflow ordering and the read-only limitation, an agent has everything needed to select and invoke the tool without further context.
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 coverage is 100%, so baseline is 3 and all three parameters are already documented. The description adds the combinatorial semantics the schema does not state: with no arguments it lists tags with operation counts, while tag and/or query (individually or together) lists matching operations. It also enumerates the returned fields, which helps an agent interpret the query parameter's effect.
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 (browse/list) and resource (the VSP 360 REST API operations) and spells out what the two modes return. It explicitly names the sibling tools vsp360_describe_operation and vsp360_call_operation, so an agent can place it in the workflow 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.
Does the description explain when to use this tool, when not to, or what alternatives exist?
"Use this first to find the operationId you need, then vsp360_describe_operation and vsp360_call_operation" gives an explicit ordering against alternatives. It also states an exclusion up front: operations marked [write] are blocked because the server runs read-only, so the agent knows not to attempt write calls.
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.
3 tool updates
v0.1.26- First observed
vsp360_call_operation - First observed
vsp360_describe_operation - First observed
vsp360_list_operations
TDQS
Scored across 3 tools
The three tools form a clean discover-describe-invoke pipeline with no functional overlap: list returns operationIds, describe returns schemas, call executes. Descriptions explicitly state the intended ordering, so an agent can never mistake one for another.
All names use the identical vsp360_ prefix followed by a consistent verb_noun pattern (list_operations, describe_operation, call_operation). The singular/plural distinction on 'operation(s)' is meaningful rather than sloppy.
Three tools is exactly right for a generic API gateway: the full VSP 360 surface is reached dynamically through operationId rather than one tool per endpoint. Every tool earns its place with no filler.
Discovery, introspection, pagination handling, binary download handling, and automatic auth cover the read lifecycle thoroughly. The deliberate read-only restriction blocks all write operations, which is a real capability gap for the domain even though it is an intentional safety design.
Maintenance
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