Search the mBlock block catalog to find available blocks for a specific device or query, helping you locate the right coding blocks for your project.
Searchable block catalog (core + imported .mext). Filter by device and query.
| Name | Required | Description | Default |
|---|---|---|---|
| query | No | ||
| device | No | sprite, mbot, cyberpi, arduino_uno, stage, all | all |
Changes observed during successful MCP inspections.
v1.0.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already provide readOnlyHint, idempotentHint, and destructiveHint, so the read-only safety profile is covered. The description adds the scope (core + imported MEXt) and searchable nature, which is useful context, but does not go beyond a basic description of behavior or include any caveats like pagination. This is adequate but not rich.
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?
The description is a single sentence that front-loads the primary verb ('Searchable') and then provides the essential scope and filters with no filler or redundant text.
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 read-only, idempotent, simple list-like tool with optional parameters and no output schema, the description packs scope (core + imported .mext) and the two filters, which is enough for an agent to invoke it correctly. It does not describe output format or pagination, but the tool category (a searchable catalog) makes those gaps low-risk.
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?
The schema explains the `device` parameter values, while `query` has no explanation. The description says the tool is 'Filter by device and query', giving `query` some semantic role (a search term), but it does not explain match behavior (e.g., substring, exact, case-sensitivity) or further clarify `device` beyond the schema. Since schema coverage is only 50%, the description only partially compensates for the undocumented query parameter.
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?
The description says 'Searchable block catalog (core + imported .mext)' and 'Filter by device and query', identifying a specific resource and action as well as scope. It is distinguishable from siblings like list_blocks by the explicit 'core + imported .mext' boundary, but it doesn't name or refer to any specific sibling.
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?
The description gives a clear use case: browsing a block catalog with filters for device and query. It does not, however, provide explicit when-to-use versus when-not-to-use guidance or point to alternative tools such as list_blocks or describe_opcode. The usage is implied rather than defined.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.