Append child blocks to a Notion parent block. Add content to pages or blocks by specifying the parent block ID and an array of block objects.
Append blocks to a parent block
| Name | Required | Description | Default |
|---|---|---|---|
| block_id | Yes | Parent block ID | |
| children | Yes | Array of block objects to append |
Changes observed during successful MCP inspections.
v1.6.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden, and it discloses nothing: no permission requirements, no note that this is an additive mutation, no ordering or positional semantics, and no per-request limits (Notion caps appended children). This is a mutation tool with zero behavioral context.
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?
A single short sentence, front-loaded and free of filler. It is arguably too terse rather than wasteful, which keeps it from a 5.
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 (2 required, documented params) and has no output schema to explain, so the description is minimally adequate. Still, for an append mutation it omits anything about return behaviour, ordering, or limits that an agent would want before invoking it.
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 100% and both parameters are documented in the schema itself, so the baseline of 3 applies. The description adds no format, nesting, or ordering detail beyond what the schema already states.
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 ('Append') and resource ('blocks') with the target ('parent block'), so an agent can tell it apart from update_block or get_block_children. It does not, however, explicitly name those siblings or clarify scope beyond the parent block.
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 indication of when to prefer this over notion_update_block or notion_create_page, and no prerequisites or exclusions. The agent must infer usage from the name alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.