LeaveManager
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., "@LeaveManagerWhat's my remaining annual leave balance?"
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.
MCP Server Setup Guide (Windows) — Leave Management Example
This README documents the full process of building a local MCP (Model Context
Protocol) server in Python with uv, testing it with MCP Inspector, and
connecting it to Claude Desktop on Windows — including the gotchas that come
up along the way.
1. Project Setup
cd Desktop\MCP
mkdir my-mcp-server
cd my-mcp-server
uv init .
uv add "mcp[cli]"Gotcha: Installing
mcp[cli]with plainpip install mcp[cli]puts it in your global Python site-packages — NOT in the project's ownuvvirtual environment.uv runonly sees packages installed viauv add(oruv pip install) inside the project. If you see:Error: typer is required. Install with 'pip install mcp[cli]'even after installing it, this is almost always the cause. Fix: run
uv add "mcp[cli]"from inside the project folder.
Related MCP server: leave_manager
2. Example main.py
Build your server using FastMCP from the mcp package: create an mcp = FastMCP("YourServerName") instance, define functions decorated with
@mcp.tool() for actions the AI can call (each with a clear docstring
describing what it does — Claude uses this to decide when to call it), and
optionally @mcp.resource("scheme://{param}") for read-only data resources.
End the file with:
if __name__ == "__main__":
mcp.run()For this walkthrough, the example server was a simple in-memory
"LeaveManager" with three tools (get_leave_balance, apply_leave,
get_leave_history) and one resource (greeting://{name}).
stdout is reserved for the JSON-RPC protocol — any stray print() corrupts
the stream and causes cryptic JSON parse errors downstream. Use logging
configured to stderr if you need debug output.
3. Test with MCP Inspector (recommended before touching Claude Desktop)
MCP Inspector is a browser-based tool for calling your tools directly — no AI, no Claude Desktop needed. Great for confirming your server actually works before wiring it into anything else.
uv run mcp dev main.pyThis opens a local page (usually http://localhost:6274). Click Connect,
then go to the Tools tab → List Tools → pick a tool → fill params →
run it and check the output.
If Connect spams
SyntaxError: Unexpected token ... is not valid JSONin the History/Notifications panel, it usually means the underlying command errored out in plain text (e.g. the same "typer is required" issue above) instead of returning JSON. Read the actual error text hiding in the syntax error message — it tells you what broke.
4. Connecting to Claude Desktop
4a. If Claude Desktop isn't installed yet
Download from https://claude.ai/download, install, and launch it at least once (finish sign-in) before doing anything else.
4b. Finding the right config file
This is the step that varies the most and caused the most confusion:
Standard installs usually use:
%APPDATA%\Claude\claude_desktop_config.json(i.e.C:\Users\<you>\AppData\Roaming\Claude\claude_desktop_config.json)Packaged/Store (MSIX) installs — recognizable by a path containing
AppData\Local\Packages\Claude_<random-id>\...— use a virtualized config location instead, e.g.:...\Local\Packages\Claude_<id>\LocalCache\Roaming\Claude\claude_desktop_config.jsonWindows silently redirects the app's "AppData\Roaming\Claude" reads/writes to this Packages folder, so editing the plain%APPDATA%\Claudecopy does nothing for this install type.Easiest way to find the right one: open Claude Desktop → Settings → Developer (under "Desktop app" section) → Local MCP servers → click Edit Config. This always opens the file the app actually reads, regardless of install type.
Dead end to avoid: Settings → Connectors → Add custom connector looks like the obvious place to add a server, but it's only for remote MCP servers (ones reachable by a URL, e.g. a hosted server on the internet). It has no field for a local command like
uv run main.py, so don't waste time there for a local stdio server — go to Developer → Local MCP servers instead.
4c. The config format
The file may already contain other keys (preferences, Cowork settings,
etc. on newer builds). Just add mcpServers as a new top-level key —
don't delete anything else:
{
"mcpServers": {
"leave-manager": {
"command": "uv",
"args": [
"--directory",
"C:\\Users\\<you>\\Desktop\\MCP\\my-mcp-server",
"run",
"main.py"
]
}
}
}If
"command": "uv"isn't found (Claude Desktop doesn't always inherit your terminal's PATH), use the full path instead, e.g.:C:\\Users\\<you>\\AppData\\Local\\Programs\\Python\\Python314\\Scripts\\uv.exe
4d. Restart and verify
Save the config file.
Fully quit Claude Desktop — right-click its icon in the system tray (bottom-right, near the clock) → Quit/Exit. Closing the window alone is not enough.
Reopen Claude Desktop.
Go to Settings → Developer → Local MCP servers — your server should show up with a green "running" badge.
Start a new chat and ask a natural question, e.g.: "How many leave days does E001 have left?" Claude should say "Loaded tools, used
<your-server-name>integration" and answer using your tool's actual return value.
5. Quick troubleshooting checklist
Symptom | Likely cause | Fix |
|
|
|
| Claude Desktop not installed, or | Install the app, or skip |
Inspector shows repeated JSON parse errors | Server process is printing plain text instead of JSON (crash message, or a stray | Check the error text embedded in the parse error; fix the underlying issue |
Settings → Developer → "No servers added" after editing config | Edited the wrong config file, or | Use Settings → Developer → Edit Config to find the actual file in use; verify JSON is valid |
Server shows up but Claude never calls it | Ambiguous tool descriptions, or server crashed silently | Check "View Logs" next to the server entry in Settings → Developer |
6. Useful commands reference
uv init . # create a new uv project
uv add "mcp[cli]" # add MCP with CLI/dev tools as a dependency
uv run mcp dev main.py # launch MCP Inspector against your server
uv run mcp install main.py # (optional) attempt auto-install into Claude Desktop
uv run main.py # run the server standalone (useful for checking for crashes)Available Tools
3 toolsapply_leaveB
Apply leave for specific dates (e.g., ["2025-04-17", "2025-05-01"])
| Name | Required | Description | Default |
|---|---|---|---|
| employee_id | Yes | ||
| leave_dates | Yes |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description provides no behavioral context beyond the action itself. It does not disclose side effects, whether approval is required, how conflicts are handled, or permissions needed. The only extra is the date array example.
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?
The description is a single sentence with a concrete example, front-loaded with the verb, and contains no redundant 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?
For a two-required-parameter mutation tool, the description omits the employee_id parameter entirely and gives no information about constraints or process. Although an output schema exists, the description does not fully compensate for the 0% schema description coverage.
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 0%. The description adds meaning only to leave_dates via an example, but leaves employee_id entirely unexplained beyond its property name. No additional semantics for employee_id are provided.
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?
The description uses a specific verb ('apply') and resource ('leave'), and the example clarifies the expected date array format. It is clearly distinct from the read-only siblings (get_leave_balance, get_leave_history).
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?
The description implies usage for requesting time off but does not explicitly state when to use this versus the sibling getter tools, nor any prerequisites or exclusion criteria. The contrast is implicit through the tool name and sibling names.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_leave_balanceC
Check how many leave days are left for the employee
| Name | Required | Description | Default |
|---|---|---|---|
| employee_id | Yes |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
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 does mention the action is to 'Check', implying a read-only operation, but it does not explicitly state whether authentication is required, what happens if the employee_id is invalid, or the format of the returned data. It also does not confirm there are no side effects, which is critical without annotations.
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?
The description is a single, concise sentence with no redundant words. It is front-loaded with the action and resource, making it easy to parse. This is appropriately sized for the tool's simplicity.
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?
The tool is simple with only one parameter and an output schema, so the description covers the core function. However, it misses usage context and does not explicitly frame it as a read-only operation. The absence of annotations and lack of comparison to siblings leaves gaps, but given the tool's simplicity, it is minimally viable.
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 0% and the description does not mention the employee_id parameter at all. The parameter name and type are self-explanatory, but the description adds no meaning about the expected format, whether it is an internal identifier, or any constraints. Given the low coverage, the description should compensate but fails to do so.
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?
The description clearly states the tool's function: checking remaining leave days for an employee. It uses a specific verb ('Check') and resource ('leave days'), which distinguishes it from generic operations. However, it does not explicitly compare against sibling tools like get_leave_history or apply_leave, so the differentiation is implied rather than stated.
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 guidance on when to use this tool versus alternatives. The description simply states what it does, but does not mention that it should be used for current balance checks, nor provide exclusions (e.g., for historical data use get_leave_history). This leaves the agent without clear decision-making context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_leave_historyC
Get leave history for the employee
| Name | Required | Description | Default |
|---|---|---|---|
| employee_id | Yes |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must carry the burden. It only states the purpose without disclosing behavioral traits such as read-only nature, response format, filtering, or pagination. Minimal disclosure of the operation.
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?
The description is a single sentence with no redundant words, making it concise and front-loaded. However, it is somewhat under-specified, but for conciseness it earns high marks.
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?
Given the existence of an output schema and one required parameter, the description is very incomplete. It does not explain expected return values, usage context, or any limitations. For a tool with no annotations, this is a significant gap.
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 0%. The description adds no information about the employee_id parameter beyond what the schema shows. It would need to explain how to specify the employee, but it does not.
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?
The description uses a specific verb 'Get' and resource 'leave history', clearly indicating the tool's function. It distinguishes from siblings like get_leave_balance (balance vs history), though it lacks detail on scope.
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 guidance on when to use this tool versus alternatives. Does not mention conditions, prerequisites, or exclusion criteria.
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
v0.1.0- First observed
apply_leave - First observed
get_leave_balance - First observed
get_leave_history
TDQS
Scored across 3 tools
Each tool clearly targets a distinct function: checking balance, applying for leave, and viewing history. No overlap or ambiguity.
All tools follow a consistent 'verb_leave_noun' pattern (get_leave_balance, apply_leave, get_leave_history), making the set predictable.
Three tools is minimal but reasonable for a basic leave manager. A few more (e.g., cancel or update leave) could be helpful, but the count is not inappropriate.
The set covers basic read and create operations but lacks essential operations like cancel, update, or approve leave, leaving significant gaps for a full leave management workflow.
Maintenance
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Related MCP Servers
- FlicenseNot gradedqualityDmaintenanceA centralized employee leave management system that allows users to check leave balances, apply for leave, and view leave history through an OpenAPI interface.9-
- FlicenseNot gradedqualityDmaintenanceEnables natural-language-based employee leave management including leave balance checks, leave applications, approvals, and history retrieval through an MCP-compatible client.-
- FlicenseBqualityCmaintenanceEnables LLMs to manage employee leave by checking balances, applying for leave, and viewing history.3-
- FlicenseCqualityCmaintenanceEnables natural language leave management, allowing users to check leave balances, apply for leave, and retrieve leave history via MCP tools.3-