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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds behavior beyond that: null semantics for missing website/about pages, contactUrl present only where one exists, and the cross-server exception for NodajiMarket with a concrete discovery pointer (/.well-known/mcp.json). It says nothing about error behavior when an app_id is unknown.

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 sentences, front-loaded with the returned fields, and every listed item maps to something the agent will actually see in the response. The NodajiMarket caveat is a single dense clause rather than padding.

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?

There is no output schema, so the description must carry return-value semantics and it does, enumerating the fields and their nullability. What remains unstated is the not-found/invalid app_id behavior, the only meaningful gap for a simple one-parameter read 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?

With a single parameter and 100% schema description coverage, the schema already tells the agent that app_id comes from nodajifi_list_apps with an example. The description adds no further meaning about the parameter or its failure modes, so the baseline 3 applies.

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 identifies the resource precisely (one app's full intro) and enumerates the payload (summary, languages, website, about/contact pages, status, dataTools), which clearly separates it from the nodajifi_list_apps sibling. It lacks an explicit retrieval verb, relying on the title's 'Get one NodajiFi app' to supply the action.

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: an agent infers this is the detail-fetch for an id obtained from nodajifi_list_apps. There is no explicit when-to-use versus nodajifi_list_apps guidance, but the description does route the agent elsewhere for NodajiMarket products and checkout via the separate mcpServer, which is genuine routing context.

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