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

The description explains the behavior for addresses without an account (grant starts working at first sign-in), adding valuable detail beyond the annotations. The annotations (readOnlyHint=false, idempotentHint=true, destructiveHint=false) are consistent with the description, which describes a non-destructive, idempotent sharing action. The description does not mention error cases or side effects, but the core behavior is 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 description is concise, consisting of two sentences that directly convey the action, the condition, and the special case for new accounts. No unnecessary words or redundancy, and it is well-structured for quick comprehension.

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 tool's simplicity (3 required parameters, no output schema, no nested objects), the description provides all necessary context: who can use it, under what condition, and how the grant behaves for new users. It is fully complete for an agent to invoke the tool correctly without further information.

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 already covers all three parameters with helpful descriptions (e.g., app_id starts with 'app_', role enum with explanatory text). The tool description adds extra context for the email parameter ('An address without an account gets a grant...') that is not present in the schema, thus enhancing parameter understanding beyond the schema's 100% coverage.

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 clearly states the action ('Give one email address access to an app') and specifies the two possible roles (viewer or editor). It also distinguishes this tool from siblings by noting the permission requirement (owner or editor) and the condition (editor-managed sharing), making the tool's purpose unambiguous.

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 provides a clear condition for when the tool can be used ('when the owner has enabled editor-managed sharing') and specifies authorized users (owner or editor). It does not explicitly name alternative tools (e.g., revoke_app_share) but the context makes the appropriate use case evident, so it earns a high score.

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