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

Annotations already declare readOnlyHint=true, idempotentHint, openWorldHint, and non-destructive, so the safety profile is covered. The description adds useful operational behavior beyond that: it discloses pagination behavior (returns count, limit, next_page_token, threads; page with next_page_token) and aligns thread fields with a known sibling tool, setting accurate expectations for the response shape.

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?

Three sentences with no filler: the primary action is front-loaded, followed by pagination/return details, and then sibling routing. Every sentence earns its place and no guidance is buried.

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 output schema exists and annotations carry the safety profile, the description covers the operational essentials: scope to one inbox, pagination flow, return field names, and how to differentiate from sibling search/listing tools. Nothing needed to call it correctly appears missing.

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 schema already documents q's matching behavior, before/after timestamps, limit, page_token, inbox_id, and Authorization. The description adds no parameter-level detail beyond what the schema provides, so the 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?

The description opens with 'Full-text search across one inbox's threads,' giving a specific verb (search), resource (threads), and scope (one inbox). It also distinguishes itself from siblings by naming get_agentmail_inbox_threads for date-ordered access and get_agentmail_inbox_messages_search for message-level search, so an agent can select the correct tool without inspecting 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?

It explicitly says get_agentmail_inbox_threads is 'the one to use for everything in date order' and points to get_agentmail_inbox_messages_search when searching individual messages rather than conversations. This gives explicit when-to-use versus alternative guidance beyond what annotations provide.

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