Read an email thread

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 a useful behavioral note about normalized plain-text bodies, but says nothing about failure modes (unknown threadId), size behavior beyond the schema's maxBodyChars, or whether all accounts are searched.

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?

One front-loaded sentence with no filler; the key scope qualifier ('all messages in a thread') sits early. It is arguably too terse for the gaps it leaves, but nothing in it is wasted.

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 read-only tool with full schema coverage and clear annotations, the description is adequate but thin: with no output schema, it gives only 'clean text bodies' and does not sketch what a returned message contains (senders, timestamps, attachments) or how a missing thread is signalled.

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 coverage is 100%: threadId, account alias with default fallback, and per-message truncation are all documented inline, including a default and min/max range. The description adds the useful semantic that truncation applies per message across the whole thread, slightly reinforcing the schema rather than repeating it.

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 (read a whole conversation / all messages in a thread) and adds a distinguishing output trait (clean text bodies). It does not explicitly name read_email as the single-message sibling, so the contrast must be inferred from 'whole conversation'.

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?

Usage is only implied: the phrase 'whole conversation (all messages in a thread)' suggests this is the right tool when the agent wants surrounding context rather than one message. There is no explicit when-to-use/when-not or named alternative such as read_email.

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