register_directory

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

With no annotations provided, the description carries the full burden and does so: it discloses the confirmation/auth requirement, the refusal condition, the scope of access granted (directory plus all subdirectories, all filesystem operations), and the runtime exclusions. These are exactly the behavioral traits an agent needs before invoking a state-changing access grant.

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?

Front-loaded with the action and its effect, then constraints, then current state. Efficient overall, though the trailing 'CURRENTLY ACCESSIBLE DIRECTORIES' line reads as dynamic state that may be better placed elsewhere; it still earns its place by signaling why registration is needed.

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?

For a no-annotation, no-output-schema access-grant tool, the description covers authorization, refusal behavior, scope, and exclusions. Nothing essential for a correct call is missing; return values need not be explained given no output schema exists.

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?

Only one parameter, and schema description coverage is 100%, so the schema already documents 'path'. The description adds no format, relative-vs-absolute, or validation detail beyond what the schema provides, making the baseline 3 appropriate.

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?

States a specific verb and resource ('Register a directory for access') and immediately explains the effect: dynamic access to human-specified directories during conversation, with all subdirectories covered for every filesystem operation. This clearly separates it from siblings like list_allowed_directories or read_file.

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?

Gives strong context and hard exclusions: registration requires user confirmation in the MCP client, is refused if no confirmation prompt exists, and filesystem roots and the home directory cannot be registered at runtime. It also notes the current state ('CURRENTLY ACCESSIBLE DIRECTORIES: None') to motivate use. It stops short of naming an alternative tool for inspecting existing access, so not a full 5.

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