Inbox summary across accounts

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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds the default scoping behavior ('covers ALL accounts by default'), which is genuinely useful, but says nothing about auth prerequisites, latency, or fan-out cost across accounts.

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?

Two sentences, front-loaded with the resource and what comes back, followed by usage triggers and a default-scope caveat. No redundant or filler clauses.

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 no output schema, the description correctly carries the return-value burden by naming counts and newest unread messages. A read-only, 3-param tool with full schema coverage needs little more, though noting the per-account fan-out cost would complete it.

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 query, latest and account are already documented including defaults and the 'all' semantics. The description only restates the default account scope ('covers ALL accounts by default'), adding no syntax or format detail beyond the schema. Baseline 3 applies.

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 resource and output shape: unread/total counts per account plus the newest unread messages. That content profile implicitly separates it from search_emails and read_email, though no sibling is named explicitly.

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?

Gives explicit invocation triggers with quoted user phrasings ('check my email', 'anything new?', 'what's unread across my accounts'). It does not state when NOT to use it or point to search_emails/read_thread for drilling into a specific message.

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