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

With no annotations, the description carries the full burden. It discloses that the tool lists all available directories, lists example categories, and returns niche IDs. While it does not explicitly state 'read-only,' the verb 'list' implies a safe read operation. It adds value by explaining the output's purpose, though it omits details like pagination or exact response structure.

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 appropriately sized, with a clear opening sentence followed by useful context. The list of categories is lengthy but provides concrete examples, making it informative rather than wasteful. It is well-structured and front-loaded.

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 simple list tool with no parameters and no output schema, the description is complete: it states the purpose, gives examples of content, and mentions the return value (niche IDs). It could be more precise about the return format, but given the simplicity, it adequately covers what the agent needs to know.

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 tool has zero parameters, and the schema is empty, so there are no parameter semantics to document. Per the baseline for 0 parameters, a score of 4 is appropriate; the description adds context about what the IDs are for, which indirectly aids understanding of the (absent) parameters.

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's function with a specific verb and resource: 'List all available service directories in the LocalPro network.' It also explains its role as the starting point and enumerates specific categories, which distinguishes it from sibling tools like list_cities and search_providers.

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?

Explicit usage guidance is provided: 'This is the starting point for discovering what categories... are available' and 'Returns niche IDs needed for all other tools.' This tells the agent when to use this tool versus others and establishes it as a prerequisite.

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