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

Annotations already mark the tool read-only, and the description repeats that but also adds meaningful behavior beyond the annotation: it describes returned fields, conditional 'for a project' behavior, and the fact that it operates against an index. No contradiction with annotations.

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 front-loads the core purpose and then lists the output fields in a structured, readable way. Each clause adds useful information, and the final two short sentences give usage and safety guidance without redundancy.

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?

With a single parameter, no output schema, and read-only annotations, the description covers what the tool returns, when to use it, and its read-only nature. The agent has enough to select and invoke it correctly without additional 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?

Schema coverage is 100% and the slug parameter is already described as 'The catalog slug, e.g. "saashub".' The description adds the context of using it before list_directories rows, but it does not add new semantics about the slug parameter itself, so the baseline of 3 applies.

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 returns one directory from the index and enumerates the exact fields returned, so an agent knows precisely what it does. It also distinguishes itself from list_directories by emphasizing 'one directory' and naming the sibling explicitly.

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 explicit guidance: 'Use it before opening a row from list_directories,' which tells the agent when this tool fits in the workflow. It does not explicitly state when not to use it or name other alternatives, but the context is clear enough.

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