fs_stat

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint. The description adds valuable behavioral context: the path is scoped to the project root and escapes are prevented via openat2, and lease_id renews if provided. This goes beyond what the annotations provide, without contradiction.

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?

Two concise sentences that front-load the core purpose and then add essential security and lease details. No filler or redundancy. Every phrase adds value.

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 a moderate-complexity stat tool, the description covers purpose, path scoping, default project, read-only nature, lease behavior, and security. An output schema exists to handle return value documentation. Missing only minor details like whether the path must exist, but overall complete for agent use.

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 zero description coverage, so the description carries the burden. It clarifies that 'path' is relative to the project root, 'project' defaults to 'demo', and 'lease_id' renews if provided. This adds practical meaning beyond the schema's bare parameter names and defaults.

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 stats a path under a registered project root, with a specific verb and resource. It distinguishes from sibling tools like fs_read and fs_list by focusing on stat (metadata) and mentions the default project. The purpose is unambiguous and specific.

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 clear context: it is read-only, operates under a registered project root, and has optional lease renewal. It does not explicitly name alternatives or exclusions, but the context is sufficient for an agent to decide when to use this tool. Lacks an explicit 'use when' statement, hence not a 5.

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