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

The description discloses substantial behavioral details beyond the annotations: registered users get an active share, unregistered ones a pending invite, and both receive an email. It also specifies ownership and API key restrictions. The annotations only indicate non-read-only and non-destructive, so this description meaningfully enriches the agent's understanding of side effects.

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 three focused sentences: the first delivers the core action and state outcomes, the second states prerequisites, and the third points to a sibling. No filler, and the most important information is front-loaded.

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 mutating action with no output schema, the description covers purpose, side effects, and authorization constraints. It does not explicitly address the conditional nature of model_id (required for user-scoped keys, ignored for model-scoped ones), but this is fully documented in the schema, so the agent can retrieve it when needed.

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 described in the input schema. The description mentions roles ('viewer or editor') aligning with the role enum but adds no parameter-specific detail that the schema doesn't already provide. Thus, it does not elevate above the schema-driven 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 opens with 'Invite an email to a model as a viewer or editor', a specific verb and resource with role options. It further distinguishes from sibling tools by pointing to layerz_list_shares for reading the roster, making the tool's purpose immediately identifiable.

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 clearly states constraints: 'Owner-only' and 'not available for read-only API keys', which tells the agent when the tool is applicable. It also directs users to layerz_list_shares as the complementary tool for viewing existing shares, though it does not explicitly mention layerz_revoke_share as the alternative for removing access.

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