get_export_part

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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false; the description adds real context beyond them by noting the call creates a metered asynchronous job and may retain delivery state, which explains why a 'retrieve' is not read-only. However, 'without inference' and 'Does not revise seller terms' are cryptic and do not clarify retry, cost, or state-retention semantics.

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?

The purpose is front-loaded and the sentences are short, but the second half drifts into clauses that do not help an agent decide or invoke: 'Does not revise seller terms' is unrelated to retrieving a part, and 'without inference' is unexplained jargon.

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?

All four required parameters are documented in the schema and there is no output schema, so the description only needs to cover flow and side effects. It covers metering and state retention but leaves open what a part response contains, whether parts can be fetched in parallel, and what happens if a part is missing or has a hash mismatch.

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%, including meanings for index, export_id, request_id and session_id, so the schema already carries parameter semantics. The description adds only the general verification requirement, not per-parameter meaning, 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 first clause gives a specific verb and resource with scope: 'Retrieve one existing resumable export part from your session.' An agent can tell this fetches a single part rather than the whole export (get_result) or status (get_status), 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?

It implies the usage pattern: retrieve every part and verify hashes before claiming completion, so the agent infers iteration until all parts are received. There is no explicit when-not or pointer to an alternative sibling such as get_result, so guidance is implied rather than stated.

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