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

With no annotations beyond title, the description carries the full burden. It discloses that apps run in a sandbox, specifies the allowed API call methods (fetch and mu.service), notes that mu.api does not exist, and warns that direct external fetch is blocked. It also advises inspecting real schemas and not inventing fields or claiming runtime verification, and states that omitted fields retain their values. This is exceptionally transparent.

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 core action is front-loaded concisely, followed by a second paragraph covering sandbox environment and coding guidance. The second paragraph is somewhat generic and long but not redundant, and every sentence adds meaningful context. The structure is clean, though the environment block could be trimmed or placed elsewhere.

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 tool with 7 parameters and no output schema, the description covers the core operation, ownership, partial update, and important environmental constraints. It does not mention return values or error cases, but those are not explicitly required and the description is sufficiently complete for an agent to call it correctly.

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 coverage is 100% with each parameter individually described. The description adds semantic value by establishing an ownership requirement ('an app you own') that is not present in the slug parameter description, and reinforces the partial-update semantics already in the schema. This goes slightly 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?

The description states a specific verb ('Edit') and resource ('an app you own') and lists the exact fields that can be edited: name, description, tags, icon, HTML or price. This clearly distinguishes it from sibling tools like apps_create (creation) or apps_read (reading), and the ownership qualifier further narrows the scope.

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?

The description implies usage for editing an existing app you own, and the explicit 'Fields left out keep their value' clarifies partial-update behavior. However, it does not explicitly contrast with alternatives such as apps_create when a new app is needed. The context is clear enough but lacks a direct 'when not to use' statement.

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