get_thread_context

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

With no annotations, the description carries the full burden but does contribute real behavior: result ordering, per-message shortening, and an explicit trust boundary marking message content as data rather than instructions. It omits failure behavior (invalid id, n larger than the thread) and whether whole messages or snippets are returned when n is small.

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, both front-loaded and free of redundancy: semantics first, then the injection-safety warning. The first sentence is slightly elliptical in dropping its verb, but no sentence 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 simple read tool with no output schema and no annotations, the description covers the core semantics and the trust boundary, which is the highest-risk aspect. It falls short on the max_chars budget semantics and on what a caller receives at thread boundaries, leaving the agent to guess at call-time correctness.

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 0% with three bare-titled parameters, so the description must compensate. It only gives meaning to 'n' (count of preceding messages); 'max_chars' is never explained (per message vs. total budget), and 'id' is left as an unnamed 'item' with no hint of its type or source.

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 names the exact resource (the n messages preceding an item in its thread) and adds distinguishing traits: ordering (oldest first) and truncation (each shortened). It is clearly distinct from siblings like get_item and list_threads, though the fragment lacks an explicit verb and opens as a noun phrase rather than 'returns/retrieves'.

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?

No when-to-use guidance is given, and no sibling is named. The agent must infer that this tool is for expanding context around a specific item rather than paging a whole thread (list_threads) or fetching a single message (get_item).

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