oassis — web scraping, crawling and browser control for AI agents

web_session_open

Opens a browser session and returns the map of controls. Opening costs 2.5 credits plus the requested outputs; the first minute is included. Further started minutes cost 2 credits with an account key. Use web_act to interact and web_session_close when done. API key and credits required. Reference: https://oassis.dev/openapi.json

Input Schema

TableJSON Schema

Name	Required	Description	Default
`pdf`	No	Options for the `pdf` format: `format` (a4, letter, legal…), `landscape`, `printBackground`, `scale` 0.1 to 2.
`url`	Yes	Page to process.
`json`	No	For the `json` format: a `prompt` describing what to pull out, a JSON `schema` to fill, or both.
`wait`	No	When to consider the page loaded: `until` (load, domcontentloaded, networkidle0, networkidle2), `selector` to wait for, `timeout` in ms.
`block`	No	What not to load, which makes a render faster and cheaper. `resourceTypes` takes image, font, stylesheet, media… and `urlPatterns` are regular expressions, not globs: `\.svg$`, not `*.svg`.
`links`	No	Options for the `links` format: `visibleOnly`, `excludeExternal` to keep only internal links.
`maxAge`	No	Accept an answer up to this many milliseconds old. A cache hit costs $0.0002 instead of the format price. Leave it out to force a fresh render.
`formats`	No	Outputs you want in the same response. `controls` is the map of what can be clicked; `elements` needs `selectors`; `json` needs `json.prompt` or `json.schema`.
`request`	No	How to make the request: `headers`, `cookies`, `userAgent`, and `auth` for basic authentication.
`binaryAs`	No	How a screenshot or a PDF comes back. `base64` is the only value today.	base64
`controls`	No	Options for the `controls` format: `visibleOnly`, and `limit` (1 to 1000) to cut the map.
`viewport`	No	The window to render in: `width`, `height`, `deviceScaleFactor`.
`selectors`	No	CSS selectors for the `elements` format.
`screenshot`	No	Options for the `screenshot` format: `fullPage` for the whole page, `type` (png, jpeg, webp), `quality` 1-100 (not with png), `omitBackground`, `selector` to capture one element, and its own `viewport`.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 19, 2026
- changedInput schema / properties / binaryAs / enum
```
Previous value: -[
-  "base64",
-  "url"
-]New value: +[
+  "base64"
+]
```
- removedInput schema / properties / json / properties / model
```
Removed value: -{
-  "minLength": 1,
-  "type": "string"
-}
```

Changed30 schema fields changedOct 4, 2026

addedInput schema / properties / binaryAs

Added value: +{
+  "default": "base64",
+  "description": "How a screenshot or a PDF comes back. `base64` is the only value today.",
+  "enum": [
+    "base64",
+    "url"
+  ],
+  "type": "string"
+}

addedInput schema / properties / block

Added value: +{
+  "additionalProperties": false,
+  "description": "What not to load, which makes a render faster and cheaper. `resourceTypes` takes image, font, stylesheet, media… and `urlPatterns` are regular expressions, not globs: `\\.svg$`, not `*.svg`.",
+  "properties": {
+    "resourceTypes": {
+      "items": {
+        "minLength": 1,
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "urlPatterns": {
+      "items": {
+        "minLength": 1,
+        "type": "string"
+      },
+      "type": "array"
+    }
+  },
+  "type": "object"
+}

addedInput schema / properties / controls

Added value: +{
+  "additionalProperties": false,
+  "description": "Options for the `controls` format: `visibleOnly`, and `limit` (1 to 1000) to cut the map.",
+  "properties": {
+    "limit": {
+      "maximum": 1000,
+      "minimum": 1,
+      "type": "integer"
+    },
+    "visibleOnly": {
+      "type": "boolean"
+    }
+  },
+  "type": "object"
+}

addedInput schema / properties / formats / default
```
Added value: +[
+  "controls"
+]
```

changedInput schema / properties / formats / description

Previous value: -"Outputs you want in the same response. `controls` is the map of what can be clicked; `elements` needs `selectors`; `json` needs `json.prompt`."New value: +"Outputs you want in the same response. `controls` is the map of what can be clicked; `elements` needs `selectors`; `json` needs `json.prompt` or `json.schema`."

addedInput schema / properties / formats / maxItems
```
Added value: +9
```
addedInput schema / properties / formats / minItems
```
Added value: +1
```
addedInput schema / properties / json / additionalProperties
```
Added value: +false
```

changedInput schema / properties / json / description

Previous value: -"For the `json` format: `prompt` and/or `schema`."New value: +"For the `json` format: a `prompt` describing what to pull out, a JSON `schema` to fill, or both."

addedInput schema / properties / json / properties / model

Added value: +{
+  "minLength": 1,
+  "type": "string"
+}

addedInput schema / properties / json / properties / prompt / minLength
```
Added value: +1
```
addedInput schema / properties / json / properties / schema / additionalProperties
```
Added value: +{}
```

addedInput schema / properties / links

Added value: +{
+  "additionalProperties": false,
+  "description": "Options for the `links` format: `visibleOnly`, `excludeExternal` to keep only internal links.",
+  "properties": {
+    "excludeExternal": {
+      "type": "boolean"
+    },
+    "visibleOnly": {
+      "type": "boolean"
+    }
+  },
+  "type": "object"
+}

addedInput schema / properties / maxAge / maximum
```
Added value: +604800000
```
addedInput schema / properties / maxAge / minimum
```
Added value: +0
```

changedInput schema / properties / maxAge / type

Previous value: -"number"New value: +"integer"

addedInput schema / properties / pdf

Added value: +{
+  "additionalProperties": false,
+  "description": "Options for the `pdf` format: `format` (a4, letter, legal…), `landscape`, `printBackground`, `scale` 0.1 to 2.",
+  "properties": {
+    "format": {
+      "enum": [
+        "letter",
+        "legal",
+        "tabloid",
+        "ledger",
+        "a0",
+        "a1",
+        "a2",
+        "a3",
+        "a4",
+        "a5",
+        "a6"
+      ],
+      "type": "string"
+    },
+    "landscape": {
+      "type": "boolean"
+    },
+    "printBackground": {
+      "type": "boolean"
+    },
+    "scale": {
+      "maximum": 2,
+      "minimum": 0.1,
+      "type": "number"
+    }
+  },
+  "type": "object"
+}

addedInput schema / properties / request

Added value: +{
+  "additionalProperties": false,
+  "description": "How to make the request: `headers`, `cookies`, `userAgent`, and `auth` for basic authentication.",
+  "properties": {
+    "auth": {
+      "additionalProperties": false,
+      "properties": {
+        "password": {
+          "type": "string"
+        },
+        "username": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "username",
+        "password"
+      ],
+      "type": "object"
+    },
+    "cookies": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "domain": {
+            "type": "string"
+          },
+          "httpOnly": {
+            "type": "boolean"
+          },
+          "name": {
+            "minLength": 1,
+            "type": "string"
+          },
+          "path": {
+            "type": "string"
+          },
+          "secure": {
+            "type": "boolean"
+          },
+          "value": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "name",
+          "value"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "headers": {
+      "additionalProperties": {
+        "type": "string"
+      },
+      "type": "object"
+    },
+    "userAgent": {
+      "minLength": 1,
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

addedInput schema / properties / screenshot

Added value: +{
+  "additionalProperties": false,
+  "description": "Options for the `screenshot` format: `fullPage` for the whole page, `type` (png, jpeg, webp), `quality` 1-100 (not with png), `omitBackground`, `selector` to capture one element, and its own `viewport`.",
+  "properties": {
+    "fullPage": {
+      "type": "boolean"
+    },
+    "omitBackground": {
+      "type": "boolean"
+    },
+    "quality": {
+      "maximum": 100,
+      "minimum": 1,
+      "type": "integer"
+    },
+    "selector": {
+      "minLength": 1,
+      "type": "string"
+    },
+    "type": {
+      "enum": [
+        "png",
+        "jpeg",
+        "webp"
+      ],
+      "type": "string"
+    },
+    "viewport": {
+      "additionalProperties": false,
+      "properties": {
+        "deviceScaleFactor": {
+          "maximum": 3,
+          "minimum": 0.1,
+          "type": "number"
+        },
+        "height": {
+          "maximum": 4096,
+          "minimum": 1,
+          "type": "integer"
+        },
+        "width": {
+          "maximum": 4096,
+          "minimum": 1,
+          "type": "integer"
+        }
+      },
+      "required": [
+        "width",
+        "height"
+      ],
+      "type": "object"
+    }
+  },
+  "type": "object"
+}

changedInput schema / properties / selectors / description

Previous value: -"CSS selectors for `elements`."New value: +"CSS selectors for the `elements` format."

addedInput schema / properties / selectors / items / minLength
```
Added value: +1
```
addedInput schema / properties / selectors / minItems
```
Added value: +1
```
addedInput schema / properties / url / format
```
Added value: +"uri"
```

addedInput schema / properties / viewport

Added value: +{
+  "additionalProperties": false,
+  "description": "The window to render in: `width`, `height`, `deviceScaleFactor`.",
+  "properties": {
+    "deviceScaleFactor": {
+      "maximum": 3,
+      "minimum": 0.1,
+      "type": "number"
+    },
+    "height": {
+      "maximum": 4096,
+      "minimum": 1,
+      "type": "integer"
+    },
+    "width": {
+      "maximum": 4096,
+      "minimum": 1,
+      "type": "integer"
+    }
+  },
+  "required": [
+    "width",
+    "height"
+  ],
+  "type": "object"
+}

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

changedInput schema / properties / wait / description

Previous value: -"When to consider the page loaded: `until`, `selector`, `timeout`."New value: +"When to consider the page loaded: `until` (load, domcontentloaded, networkidle0, networkidle2), `selector` to wait for, `timeout` in ms."

addedInput schema / properties / wait / properties / selector / minLength
```
Added value: +1
```
addedInput schema / properties / wait / properties / timeout / maximum
```
Added value: +60000
```
addedInput schema / properties / wait / properties / timeout / minimum
```
Added value: +100
```
changedInput schema / properties / wait / properties / timeout / type
```
Previous value: -"number"New value: +"integer"
```

First observedSep 29, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations already declare the safety profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false, openWorldHint=true), so the description's added value is the cost model (2.5 credits plus requested outputs, first minute included, 2 credits per further started minute) and the API key/credit requirement. That is genuinely useful pre-invocation context, though it omits session lifetime/expiry behavior.

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?

Five short sentences, front-loaded with purpose, then cost, then next-step routing, then prerequisites and a reference link. No filler, though the two cost sentences could be tightened.

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?

For a 14-parameter tool with full schema coverage and no output schema, the description covers purpose, cost, auth needs, and workflow handoff, and states the return value (map of controls). Remaining gaps like session expiry are minor given the schema's completeness.

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 each parameter carries its own inline description (pdf, json, wait, block, screenshot, formats, etc.), so the schema already does the heavy lifting. The description only alludes to "the requested outputs" without adding syntax or format detail beyond the schema, matching the baseline of 3.

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?

States a specific verb and resource: "Opens a browser session and returns the map of controls." It also distinguishes itself from siblings by naming the follow-up tools (web_act to interact, web_session_close when done), so an agent can place it in the workflow without opening the schema.

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?

Gives clear lifecycle context: interact via web_act and close with web_session_close when done, plus API key/credit prerequisites. It does not address when NOT to open a session versus one-shot siblings like web_scrape, so the routing guidance is clear but not exhaustive.

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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