web-basics-mcp

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fetch_url

Read-onlyIdempotent

Fetch any public URL and receive clean Markdown, PDF text, or direct data, with a start_index to resume truncated content.

Instructions

Fetch one public HTTP(S) URL. Returns clean Markdown for pages and Reddit posts, extracted PDF text, direct text data, or a supported image. Use start_index to continue truncated text.

Input Schema

TableJSON Schema

Name	Required	Description
`url`	Yes	Target URL
`max_length`	No	Maximum text characters to return
`start_index`	No	Character index to start text content from

Output Schema

TableJSON Schema

Name	Required	Description	Default
`url`	Yes
`links`	No
`title`	No
`content`	No
`metadata`	No
`extractor`	Yes
`pageCount`	No
`truncated`	No
`wordCount`	No
`byteLength`	No
`contentType`	Yes
`start_index`	No
`total_chars`	No
`returned_chars`	No
`fallback_reason`	No
`next_start_index`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedv0.5.0Aug 26, 2026

addedInput schema / properties / max_length

Added value: +{
+  "default": 8000,
+  "description": "Maximum text characters to return",
+  "maximum": 20000,
+  "minimum": 1,
+  "type": "integer"
+}

addedInput schema / properties / start_index

Added value: +{
+  "default": 0,
+  "description": "Character index to start text content from",
+  "minimum": 0,
+  "type": "integer"
+}

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "byteLength": {
+      "minimum": 0,
+      "type": "integer"
+    },
+    "content": {
+      "type": "string"
+    },
+    "contentType": {
+      "type": "string"
+    },
+    "extractor": {
+      "enum": [
+        "defuddle",
+        "readability",
+        "unpdf",
+        "reddit",
+        "text",
+        "image"
+      ],
+      "type": "string"
+    },
+    "fallback_reason": {
+      "type": "string"
+    },
+    "links": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "metadata": {
+      "additionalProperties": {
+        "type": [
+          "string",
+          "number",
+          "boolean",
+          "null"
+        ]
+      },
+      "type": "object"
+    },
+    "next_start_index": {
+      "minimum": 0,
+      "type": "integer"
+    },
+    "pageCount": {
+      "minimum": 1,
+      "type": "integer"
+    },
+    "returned_chars": {
+      "minimum": 0,
+      "type": "integer"
+    },
+    "start_index": {
+      "minimum": 0,
+      "type": "integer"
+    },
+    "title": {
+      "type": "string"
+    },
+    "total_chars": {
+      "minimum": 0,
+      "type": "integer"
+    },
+    "truncated": {
+      "type": "boolean"
+    },
+    "url": {
+      "type": "string"
+    },
+    "wordCount": {
+      "minimum": 0,
+      "type": "integer"
+    }
+  },
+  "required": [
+    "url",
+    "contentType",
+    "extractor"
+  ],
+  "type": "object"
+}

First observedv1.0.0Jun 23, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds useful behavior: it specifies supported content types (Markdown, PDF text, etc.) and discloses that text can be truncated, with a pointer to start_index for continuation. No contradiction with annotations.

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?

Two sentences with zero filler. The main action and return types are front-loaded, and the start_index hint is a separate, purposeful clause. Nothing extraneous.

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

Completeness4/5

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

Given the presence of an output schema and the simple nature of the tool, the description covers the essential aspects: what it fetches, what it returns, and how to handle truncation. It does not mention error cases or rate limits, but those are not critical for correct invocation and are partially implied by the annotations.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% describing all three parameters. The description supplements the start_index parameter by explicitly connecting it to truncated text continuation, which adds semantic value beyond the generic schema description. max_length and url are already well-documented 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 clearly states the action ('Fetch') and the resource ('one public HTTP(S) URL'), and enumerates the output types. This unambiguously distinguishes it from the sibling web_search (which searches rather than fetches a known URL).

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

Usage Guidelines3/5

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

The description implies usage: you should use this tool when you have a specific URL to fetch. However, it never explicitly contrasts with web_search or states when NOT to use it. The only usage hint provided is about start_index for continuing truncated text, which is a parameter-level instruction, not a tool-selection guideline.

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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