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

The readOnlyHint annotation is already present)Skip the description reinforces it with "Read-only." More importantly, it adds context beyond the annotation: account_required behavior (page redirected to sign-in when probed), founder_fills being a form an agent cannot drive, and the presence of a last-session note. These field-level behaviors meaningfully shape how the agent should interpret results.

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 front-loaded with the core purpose, but the field list is a long, dense run-on sentence with multiple parentheticals and em-dash asides. While each detail adds value, readability suffers. The closing two short sentences provide good structure, but the middle could be better organized.

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 single-record getter with one parameter, a read-only annotation, and no output schema, the description is quite complete. It enumerates all returned fields Bonus includes field-level quirks (sign-in redirect, non-drivable form) and a specific instruction to read the note before opening the page. No critical behavior seems missing.

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 input schema already documents the only parameter (slug) with an example ("saashub") and 100% coverage. The description adds no additional slug semantics. Baseline 3 is appropriate since the schema carries the full burden.

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: "One directory from the index" — this is clearly a single-record retrieval tool. The long field list (domain rating, dofollow, price, etc.) further differentiates it from siblings like list_directories or get_submission_kit. An agent can unambiguously identify what this tool returns.

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 implies the usage context: when you need one directory's record with detailed fields, use this tool. It also gives an explicit, actionable workflow instruction: "Read the note before opening the page." It does not explicitly name alternatives or exclusions, 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.