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

With no annotations, the description must carry the behavioral burden. It signals a read operation and usefully discloses that the response includes how_to and the signed payload. It does not cover auth, error behavior, or what the signed payload is for, but for a simple read this is a moderate gap.

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?

One short, information-dense sentence with the identifying selector and key response highlights. Every phrase earns its place and nothing repeats the schema.

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-parameter read tool with no output schema, this is nearly complete: it tells the agent what id to supply and what to expect back. The explicit mention of how_to and the signed payload is valuable; omissions such as auth or not-found behavior are less important for invocation.

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 schema provides 100% coverage for the only parameter, including the source ('from search_apps') and an example prefix. The description adds the term 'opaque id', but the schema already does most of the work.

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 action ('Get one listing') and a resource ('by opaque id'), plus distinctive response contents (how_to and signed payload). This clearly separates it from search_apps and the mutation siblings.

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?

Implies the tool is for fetching an already-known app id, and the schema reinforces this with 'App id from search_apps'. However, it never explicitly says when not to use it or points to alternatives, leaving the routing partly implicit.

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