fs_is_file_exists

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

No annotations are provided, so the description must carry the full burden of behavioral transparency. It only states what the tool does, not what it returns (e.g., boolean? error on missing?), whether it follows symlinks, or what 'entry' encompasses (file/directory). The description is minimal and leaves critical operational behavior implicit.

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 with no fluff, which is structurally efficient. However, it borders on under-specification, as it omits any detail about return behavior or usage context. For such a simple tool, brevity is acceptable, but it could be improved without adding unnecessary length.

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 simplicity, one would expect a brief description to suffice, but the lack of return-type information and usage guidance makes it incomplete for an agent to know how to interpret the result. The presence of an output schema helps but is not shown here; the description itself does not round out the context.

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 has 0% description coverage for file_path, and the description does not compensate. While the parameter name is self-explanatory, the description adds no additional meaning—such as expected format, whether it supports relative/absolute paths, or how the existence check handles invalid inputs.

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 'Check filesystem entry existence.' clearly states the tool's purpose with a specific verb ('check') and resource ('filesystem entry'), and it distinguishes itself from sibling tools that perform operations like deletion (fs_delete_file) or reading (fs_read_full_text). It is immediately clear this is an existence test.

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 no guidance on when to use this tool vs alternatives. It does not mention that it could be a prerequisite before other operations, nor does it state when it should be avoided. Sibling tools like fs_get_file_info also check path validity, so usage context is ambiguous.

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