Frida Agent MCP

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

No annotations are provided, so the description carries the full burden. It mentions that messages are 'collected from the injected script's send() calls,' which adds some behavioral context about data source. However, it lacks details on permissions, rate limits, or what happens if no messages are available, leaving gaps for a mutation-free tool.

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 well-structured and concise: a purpose statement, usage guideline, and parameter explanations in a bullet-like format. Every sentence adds value without redundancy, making it easy to parse and front-loaded with key information.

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 no annotations and no output schema, the description is moderately complete. It covers purpose, usage, and parameters, but lacks details on return values, error handling, or integration with siblings like 'spawn_and_inject'. For a tool with 3 parameters and complex context, more behavioral info would enhance completeness.

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%, so the description must compensate. It explains all three parameters: 'limit' for maximum messages, 'offset' for pagination, and 'save_to_file' for saving to JSON. This adds meaningful semantics beyond the schema's basic types and defaults, though it doesn't cover edge cases like file paths or validation.

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: 'Get messages collected from the injected script's send() calls.' It specifies the verb ('Get') and resource ('messages'), and provides context about their origin. However, it doesn't explicitly differentiate from sibling tools like 'logcat' or 'execute', which might also retrieve data, so it doesn't reach the highest 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 includes a usage guideline: 'Call this after the user has triggered the target functionality.' This provides clear context on when to use the tool. However, it doesn't specify when not to use it or name alternatives among siblings, such as when to use 'logcat' instead, so it's not a perfect 5.

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