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

With no annotations, the description carries the full burden and does so: credentials are validated with the network before storage, invalid input returns 400 credentials_invalid with nothing saved, credentials are encrypted at rest and never echoed, admin key required, sandbox never publishes. These are exactly the mutation/auth safety facts an agent needs.

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?

Dense and front-loaded with the core purpose and the alternative routing, and every clause carries information. Slightly run-on phrasing ("enforces the real limits of the network in simulates") costs a point on readability, but nothing is 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?

For a complex nested-credential mutation with no annotations and no output schema, the description covers auth, validation failure, encryption, and alternatives. The remaining gap is that it never says what a successful call returns (e.g., the created channel object), which matters since no output schema exists.

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 only 40%, but the description compensates by spelling out the credentials shape per network (bluesky handle+app_password, identifier alias, facebook token+page_id, instagram token+ig_user_id) and that simulates is sandbox-only. Only brand_id and label are left to the schema, and those are self-evident.

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?

States a specific verb and resource ("Add a channel directly (admin key)") and immediately differentiates itself from the connect_channel sibling for the no-credentials case. Network-specific variants are enumerated so the agent knows exactly what is being created.

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?

Explicitly routes the agent: use this tool with an admin key when credentials exist; use connect_channel when the owner must tap a link; use a sandbox channel for testing without credentials. The "No credentials to hand?" sentence names the alternative and the condition that selects it.

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