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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description's 'Free and read-only' largely restates those hints, though 'Free' (no cost) is a small addition annotations don't carry. No pagination, permission, or rate-limit context is added.

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?

A single dense sentence, front-loaded with the core purpose, followed by the optional-scoping case and the cost note. No wasted clauses, though the sentence is long and packs several ideas together.

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 4-optional-param read tool with an output schema (so return values need no explanation) and annotations covering safety, the description supplies enough: purpose, optional targets, and the troubleshooting scenario. It does not explicitly state that all params are optional or that omitting them yields the general summary.

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?

With 0% schema description coverage, the description must carry the params, and it does: it names account, folder, source and mail_id and explains they are target selectors that turn the general answer into a specific 'why can't I see this' reply. It implies they are optional but doesn't detail the format of mail_id or folder beyond naming them.

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+resource: it explains what a connection can read, which access profiles apply, and why something is or isn't visible. Clear and specific about output. It does not explicitly differentiate itself from the sibling check_permissions or explain_policy, which is the only thing keeping it from a 5.

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 clear context: use it without filters to summarize what a connection can read, or with a named account/folder/source/mail_id to answer 'why can't I see this'. This is a real use case, but it never names an alternative tool or states when not to use it.

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