stackexchange-mcp-server

List Stack Exchange Sites

stackexchange_list_sites

Read-onlyIdempotent

Enumerate all sites in the Stack Exchange network — name, api_site_parameter, audience, and URL. The api_site_parameter value is what other tools accept as the site input (e.g. "stackoverflow", "superuser", "serverfault"). Results are fetched live and optionally filtered by name. Use this tool to discover valid site parameters before calling other stackexchange_* tools.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`filter`	No	Optional case-insensitive name filter — returns only sites whose name contains all provided tokens. Omit to return all sites.

Output Schema

TableJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`sites`	No	Stack Exchange network sites matching the optional name filter.
`notice`	No	Actionable guidance when results are empty or filtered.
`quotaMax`	No	Maximum API quota calls per day (300 keyless, ~10,000 with API key).
`totalCount`	No	Total number of sites returned after filtering.
`quotaRemaining`	No	Remaining API quota calls for the current day.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 10, 2026

changedOutput schema / properties / error / properties / data / properties / reason / description

Previous value: -"Machine-readable failure mode."New value: +"Machine-readable failure mode. Declared by this tool: `quota_exceeded`: The Stack Exchange API quota_remaining reached 0 during the site page walk. `invalid_parameter`: Stack Exchange rejected a parameter of the /sites request and named the field. `invalid_api_key`: Stack Exchange does not recognize the API key this server is configured with. `upstream_unavailable`: Stack Exchange answered with a body that is not the expected JSON envelope. Other values are possible when a failure originates below the handler."

addedOutput schema / properties / error / properties / data / properties / reason / examples

Added value: +[
+  "quota_exceeded",
+  "invalid_parameter",
+  "invalid_api_key",
+  "upstream_unavailable"
+]

Changed6 schema fields changedAug 22, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "sites",
+      "totalCount",
+      "quotaRemaining",
+      "quotaMax"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode.",
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "sites",
-  "totalCount",
-  "quotaRemaining",
-  "quotaMax"
-]

First observedJun 7, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already convey read-only, idempotent behavior, so the description correctly adds value with 'Results are fetched live,' which tells the agent results come from a live network call rather than a cached snapshot. There is no contradiction with the 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 three sentences of relevant, front-loaded information. The second sentence about api_site_parameter is useful for linkage to sibling tools, but 'optionally filtered by name' is a minor repetition of the schema.

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

Completeness5/5

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

The tool has one optional parameter, a complete input schema, and an output schema, so the description only needs to communicate usage context and behavioral traits. It covers the fields returned, the live-fetch behavior, and the discovery purpose, leaving no significant gap for the agent to call it correctly.

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 100%, and the filter parameter is fully documented in the input schema (case-insensitive, token containment, omit-to-get-all). The prose description only restates 'optionally filtered by name' and does not add meaning not already in the schema.

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 names a specific verb ('Enumerate'), a concrete resource ('all sites in the Stack Exchange network'), and the fields returned (name, api_site_parameter, audience, URL). It also positions itself relative to sibling stackexchange_* tools by saying it is for discovering valid site parameters, making its purpose unambiguous.

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 explicitly tells the agent when to use it: 'Use this tool to discover valid site parameters before calling other stackexchange_* tools.' This gives clear context, though it does not spell out contrasts with each sibling tool or list exclusions.

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

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