Create a publisher block list for a Meta ad account to exclude unwanted publishers and control where your ads appear.
Create a new publisher block list for the ad account.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | Name for the block list | |
| account_id | No | Ad account ID to create the block list in (e.g. 'act_123' or '123'). Falls back to META_AD_ACCOUNT_ID env var if omitted. |
Changes observed during successful MCP inspections.
v1.6.1Input schema / properties / account_idAdded value: +{
+ "description": "Ad account ID to create the block list in (e.g. 'act_123' or '123'). Falls back to META_AD_ACCOUNT_ID env var if omitted.",
+ "type": "string"
+}v1.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden: it implies mutation but says nothing about required permissions, whether list names must be unique, whether duplicates overwrite or error, or what is returned. For a write tool with zero annotation coverage this is a significant gap.
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 front-loaded sentence with no waste. It is efficient, though the brevity is partly the cause of the missing guidance rather than a virtue in itself.
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 mutation tool with no annotations and no output schema, the description should say what a successful creation yields (e.g. an ID) and how errors/duplicates behave. None of that is present, leaving the agent under-informed about outcomes.
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 coverage is 100%, with both name and account_id fully documented in the schema, including the env-var fallback for account_id. The description adds no parameter meaning beyond the schema, so baseline 3 applies.
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 and resource ('Create a new publisher block list') scoped to the ad account, which distinguishes it from list_block_lists, add_to_block_list, and delete_block_list. It doesn't explicitly name those siblings, but the create verb makes the distinction clear.
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 versus the sibling block-list tools, nor any prerequisites such as needing an existing ad account or how block lists are then populated via add_to_block_list. 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.