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

The readOnlyHint annotation already tells the agent this is a safe read, so the description's added load is lighter. It adds the underlying REST endpoint (GET /v2/listings/{id}), which is mildly useful context, but says nothing about auth needs, 404 behavior for a missing id, or response shape.

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 short sentences, front-loaded with the action and scope, with the endpoint as a compact second clause. No filler.

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-resource read with readOnlyHint already declared and no output schema to explain, the description covers what an agent needs to invoke it correctly. It stops just short of noting failure modes or the sibling routing, which would make it fully complete.

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 is one parameter and schema description coverage is 100%, so the schema already documents 'The listing id.' The description only restates that the lookup is by id, adding no format or origin detail beyond the schema baseline.

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 (Fetch), a specific resource (a single channel listing), and the selection key (by id). This cleanly separates it from list_listings and the other get_* siblings without the agent needing to open the schema.

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?

Usage is only implied: the id-based lookup dictates when you'd reach for it. It never names the alternative (list_listings) or states a when-not condition, so the agent must infer routing from the phrasing alone.

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