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

Annotations already indicate mutation (readOnlyHint=false) and non-idempotency. The description adds value beyond that by disclosing the return shape ({ id, orgId, name, slug, createdAt }), clarifying the app's role as owner of environments and secrets, and explaining the boundary with create_env and setup_local_crypto.

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 compact and front-loaded with the core purpose. The only weakness is the third sentence's awkward phrasing ('Creating its environments does NOT: create_env mints...'), which is grammatically clunky but still conveys a crucial distinction.

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?

Given the lack of an output schema, the description compensates by listing the exact return object. It also provides enough setup context to prevent an agent from misusing this tool for environment creation. It could be slightly richer on the org parameter's behavior, but the schema already covers that.

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?

Schema description coverage is 100%, and the schema already provides thorough explanations for org, name, and slug, including immutability of slug and the conditional behavior of org. The description adds no parameter-specific semantics beyond what the schema already documents, so the baseline score of 3 is appropriate.

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 states a specific verb and resource: 'Create an application — the container that will own environments and secrets.' It clearly distinguishes the app entity from related siblings like create_group and delete_app, and even clarifies that creating the app is not the same as creating its environments.

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?

It explicitly explains when this step is appropriate: 'This step needs no key material, so it runs here.' It also warns against expecting environment creation here, pointing to create_env and setup_local_crypto as the correct tools for that separate concern.

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