arc-mcp

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 effectively describes a key behavioral trait: 'Requires Arc restart to see in sidebar,' which is crucial for understanding the tool's impact. However, it doesn't mention other potential behaviors like error conditions, permissions needed, or what happens if the space doesn't exist.

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 two sentences with zero waste: the first states the purpose, and the second provides critical behavioral and usage guidance. Every sentence earns its place, and it's appropriately front-loaded with the core action.

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 (4 parameters, no output schema, no annotations), the description is mostly complete. It covers purpose, key behavioral constraint, and usage guidelines. However, it lacks details on error handling or response format, which would be helpful for a mutation tool with no annotations.

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 description coverage is 100%, so all parameters are documented in the schema. The description doesn't add any parameter-specific information beyond what's in the schema (e.g., it doesn't explain 'space' or 'url' further). This meets the baseline of 3 when the schema does the heavy lifting.

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 specific action ('Add a new tab') and resource ('to an Arc browser space'), distinguishing it from sibling tools like 'open_url' (for immediate opening) and 'create_space' (for creating spaces rather than tabs). It provides a complete verb+resource+scope statement.

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 explicitly states when to use this tool ('Add a new tab to an Arc browser space') and when not to use it ('Requires Arc restart to see in sidebar. For immediate opening, use open_url instead'), providing clear alternatives and exclusions. It directly addresses the trade-off between this tool and 'open_url'.

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