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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, yet the description still adds real behavioral context: agent-scoped bearer keys are required and member/facility keys cannot impersonate, receipt semantics are not proof of handling, and denial behavior is called out. The main weakness is that the auth/scope material is somewhat repetitive rather than additive.

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 deprecation notice is correctly front-loaded, but the description is dense and repeats itself ('needs agent.inbox.read' followed later by 'Required scopes: agent.inbox.read'). Several clauses about rollout switches, SQL authorization, and key substitution are of marginal value and add bulk without clear routing benefit.

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?

With an output schema present, return values need no explanation, and the description covers the remaining essentials: deprecation/replacement, required scopes, auth model, filtering scope, and caveats about receipt interpretation. An agent has everything needed to decide and invoke 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 description coverage is 100%, so both parameters (limit, item_id) are already documented in the schema. The description only restates 'Optional item_id filters one item' without adding syntax or semantics beyond what the schema provides, making the baseline 3 correct.

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 ('Read current authorized inbox retrieval receipts and agent-reported outcomes through /v1/agent-inbox/activity') and immediately flags itself as a deprecated alias for the sibling get_inbound_activity. An agent can identify the tool's function and its relationship to alternatives without consulting the schema.

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 opening 'Deprecated: use get_inbound_activity' explicitly routes the agent to the replacement, and it clarifies this alias is 'still served unchanged during the alias window.' It also supplies the conditions for use (agent.inbox.read required; agent.read for sample activity), leaving nothing to inference.

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