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

With no annotations, the description carries the full burden and does so: it discloses the side effects (move to Inbox, unblock sender), the idempotent no-op condition, per-thread isolation on partial failure, and the exact error condition (only when none succeeded). It even documents the response shape ('results', 'succeeded', 'failed') despite no output schema.

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 primary action and its main side effect are in the first sentence, with batching and failure semantics following. It is one dense block covering a lot of ground, slightly heavy but every clause is load-bearing for a batch mutation tool.

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 single-parameter batch mutation with no annotations and no output schema, nothing material is missing: side effects, no-op behavior, partial-failure handling, result ordering, and aggregation counts are all described.

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%, so baseline is 3; the description adds real value by explaining that conversation_id accepts a list and that results are returned in the order given, linking the parameter shape to observable behavior. It does not restate the 50-id cap, but the schema already does that.

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: puts a spam-filed thread back into the mailbox Inbox and unblocks its sender. This is clearly distinct from report_spam (the inverse) and unblock_sender (sender-only, no thread move), so an agent can route correctly.

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 explicit batching guidance — pass a list of ids in ONE call rather than one call per thread — which is the main usage decision for this tool. It also covers the no-op case (thread not in Spam is left alone, nothing unblocked). It does not explicitly name report_spam or unblock_sender as alternatives, which keeps it below a 5.

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