Obsidian MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool counts words and characters, implying a read-only operation, but doesn't clarify if it requires specific permissions, how it handles errors (e.g., invalid file paths), or what the output format looks like (e.g., structured data vs. raw text). For a tool with 5 parameters and no annotations, this leaves significant behavioral gaps.

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 extremely concise and front-loaded: a single sentence that directly states the core functionality and default behavior. Every word earns its place with no redundancy or fluff, making it efficient for quick understanding.

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?

Given the tool's moderate complexity (5 parameters, no annotations, no output schema), the description is incomplete. It lacks details on parameter usage, output format, error handling, and differentiation from siblings. While concise, it doesn't provide enough context for an agent to reliably invoke the tool without guessing at parameter meanings or behavioral 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 description coverage is 0%, meaning none of the 5 parameters have descriptions in the schema. The tool description only implies the 'file' parameter via 'active file' and hints at 'words' and 'characters' as metrics, but doesn't explain 'vault', 'path', or the boolean nature of 'words' and 'characters'. It adds minimal semantic value beyond the schema's titles, failing to compensate for the low coverage.

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 clearly states the tool's purpose: 'Count words and characters' with the specific resource being 'active file' by default. It uses a specific verb ('Count') and identifies the resource scope. However, it doesn't explicitly differentiate from potential sibling tools like 'obsidian_file_info' that might provide similar metrics, keeping it from a perfect score.

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 provides minimal usage guidance: 'default: active file' suggests it operates on the current file if no parameters are specified. However, it offers no explicit guidance on when to use this tool versus alternatives like 'obsidian_file_info' or 'obsidian_read', nor does it mention any prerequisites or exclusions. This lack of comparative context limits its helpfulness.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.