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

Annotations already cover readOnly/idempotent/non-destructive safety, so the description adds value by disclosing default ordering ('newest first') and the fact that bodies are omitted from results — return-shape behavior not present in the schema. It stops short of describing pagination/response envelope behavior.

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 core behavior and the get_email pointer before the filter enumeration. The filter list is dense but each item corresponds to a distinct capability and none is 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?

For a 14-parameter read tool with no output schema, the description covers the identity, default ordering, body omission, and most filter axes. Gaps remain around the pagination envelope and sortOrder interaction, which the schema only partially documents.

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 only 50% schema description coverage across 14 parameters, the description carries real weight: it maps filter dimensions to mailboxes, campaignId, threadId, leadId, isUnread, type ('sent'/'received'), folder, search, date range and latestOfThread. It omits limit, cursor, and the existence of sortOrder (which could override the stated 'newest first').

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 with scope ('across all mailboxes (unified inbox)') and immediately distinguishes itself from get_email by declaring it returns items 'without bodies'. An agent can tell exactly what this tool returns and how it differs from the retrieval sibling.

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 routes body retrieval to get_email and explains that latestOfThread collapses to one row per conversation, which is actionable selection guidance. It does not mention when to prefer siblings like count_unread_emails for counting, so it stops short of full alternative coverage.

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