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

Beyond the read-only and closed-world annotations, the description adds exhaustive scope through "Every live trade" and discloses that a town-page path is present only where one exists. It gives useful result behavior for a simple listing, though it does not cover ordering or other response mechanics.

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 compact statements front-load the returned content and then explain how to use the key, with no filler. Despite the fragmentary wording, the scope and workflow remain easy to understand.

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 zero-argument, annotated read-only list tool, the definition supplies scope, principal output fields, conditional path behavior, and downstream key usage. This adequately compensates for the absent output schema for purposes of selecting and invoking the tool.

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?

There are no input parameters, so the zero-parameter baseline of 4 applies. The description additionally clarifies the semantic role of a returned service key as input to find_pros.

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?

Defines the listing as every live trade and specifies the service key, plain label, and optional town-page path included for each. The reference to find_pros also distinguishes its directory-enumeration role from professional search.

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?

Explicitly tells the agent to pass a returned key to find_pros as its "service" input, providing a concrete downstream workflow. It does not explain when other siblings such as list_towns or get_town_summary would be preferable, but the main use case is clear.

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