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

The annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds meaningful behavioral context on top: `read_only` entries are platform-managed and cannot be deleted, and the account-wide scope can surface entries from inboxes other callers created. No contradiction with annotations is present.

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 sentences and front-loads the core purpose and returned fields before caveats. There is slight redundancy between 'organization-wide view spanning every inbox' and 'reaches inboxes other callers created,' but overall it is efficient and free of filler.

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 read-only annotations, fully documented schema, presence of an output schema, and a description that covers scope, shared-account implications, and the precise sibling to use instead, an agent has all the information needed to decide and invoke correctly. No critical gap stands out.

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 the baseline is 3. The description lists output fields like `entry_type` and `list_type` but does not add new meaning about the four required input parameters themselves; it neither clarifies nor repeats what the schema already documents.

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 a specific verb and resource, 'Fetches one account-wide allow or block entry,' and enumerates the exact fields returned. It explicitly contrasts itself with the inbox-scoped sibling, so an agent can disambiguate the two list-entry getters without opening their schemas.

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 explicitly states this is the organization-wide view spanning every inbox, warns that it reaches entries created by other callers in the shared AgentMail account, and names the alternative tool (`get_agentmail_inbox_list_entry`) to use when a single inbox is intended. This is clear, actionable routing guidance.

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