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

Annotations already declare readOnly/idempotent/non-destructive, yet the description adds substantial context beyond them: required scopes (agent.inbox.read, agent.read), that an agent-scoped bearer key is mandatory and member/facility keys cannot impersonate an agent, Vault unavailability, and the 'never substitute another key or mail API after denial' constraint. It also clarifies that handling version differs from OCR context_version. This is rich behavioral disclosure.

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 and purpose are correctly front-loaded, but the body is a dense run-on that mixes high-value facts (scopes, key restrictions) with low-signal implementation trivia such as 'Rollout switches, current member approval, assignment, credential environment and SQL authorization are shared with REST.' For a one-parameter read tool the prose is oversized and could be tightened.

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?

An output schema exists, so return values need not be explained. Given the tool's complexity, the description covers auth model, scoping, deprecation status, version semantics and constraints — enough for an agent to invoke it correctly and know when not to.

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 a single required UUID parameter already fully documented in the schema. The description only echoes the path id via ':id' and adds no format or sourcing nuance beyond 'from a list or search result' already present in the schema. Baseline 3 is appropriate.

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 /v1/agent-inbox/:id/handling capabilities, version and history.' This clearly distinguishes it from siblings like get_agent_inbox_activity, get_agent_inbox_context and get_agent_inbox_scan. The deprecation banner front-loads a redirect to get_inbound_item, which slightly muddies but does not obscure the purpose.

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 names the alternative ('Deprecated: use get_inbound_item. Still served unchanged during the alias window') and scopes applicability ('Gated private-mail Live and member-sample Sandbox workflow only; no generated fixtures or managed-PMB fallback'). That is strong when-to-use routing, though it does not describe the window's end condition or a fallback beyond the alias.

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