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

Annotations declare readOnlyHint: true and openWorldHint: false, covering the read-only nature. The description adds context about the data returned (stance over time, including change points), which goes beyond annotations. However, it does not disclose potential limitations like whether results are paginated, ordered by time, or how the optional thread_id affects scope. With annotations covering safety, the description provides moderate added value, justifying a 3.

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 description is a single, compact sentence that front-loads the core concept ('stance over time per discussion') and then adds detail about change points. There is no redundant or filler content. It is slightly under-structured (could be two sentences for readability), but it is efficient and scannable, earning a 4.

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?

The tool has only two parameters, is read-only, and has no output schema, so the description is the primary source of behavioral information. It conveys the essential purpose, but leaves ambiguity about the optional thread_id: does omitting it return history across all discussions or is it required for a specific discussion? The phrase 'per discussion' suggests scoping, yet thread_id is optional. Also, the return format (e.g., list of stances with timestamps) is implied but not explicit. These gaps prevent a higher score, but the overall simplicity of the tool means a 3 is adequate.

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?

The input schema has 100% description coverage for both parameters (thread_id and agent_name), so the schema already documents their meaning. The description reinforces the role of thread_id ('per discussion') and agent_name ('participant'), but adds no new syntax or format details beyond the schema. Per the baseline rule for high coverage, a 3 is appropriate.

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 clearly states the tool's purpose: retrieving a participant's stance history over time per discussion, including change points. It is specific enough to distinguish from siblings like get_stance_changes (which likely focuses on changes) and get_recent_opinions (recent opinions). The verb 'get' and resource 'stance history' are explicit, and the mention of 'when and after which opinion they changed their mind' adds clarity. However, it does not explicitly contrast with similar siblings, so a 4 rather than 5.

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 guidance is provided on when to use this tool versus alternatives. The description only explains what it does, not when an agent should choose it over get_stance_changes or get_recent_opinions. Given the presence of multiple stance-related siblings, explicit usage conditions or a mention of an alternative would be valuable, but none exist. This is a clear gap.

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