get_grouping_config

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

Annotations already declare readOnly, idempotent, openWorld and non-destructive behavior, so the safety profile is covered. The description adds genuinely non-structured traits: it is scoped to the issue's latest event (not its full history) and enumerates the per-variant breakdown returned (contributes, hash, hint, summary). It says nothing about permissions or rate limits, which keeps it out of the top band.

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, front-loaded with the purpose before the return-shape detail and the sibling pointer. The per-variant enumeration is dense but earns its place given there is no output schema; a slightly tighter phrasing could trim it further.

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?

With no output schema, the description carries the burden of describing returns, and it does so at a useful level of detail (config plus per-variant contributes/hash/hint/summary). For a one-parameter read-only tool that is close to sufficient; missing only edge cases such as behavior when the issue has no events.

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?

There is a single parameter with 100% schema description coverage, and the schema already explains that it accepts a numeric ID or short ID such as PROJ-1A2. The description adds no format, default, or validation detail beyond that, so the schema does the work and the baseline of 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 description uses a specific verb+resource ('Explain why events are grouped into an issue') and adds the operating detail that it works off the issue's latest event. It explicitly distinguishes itself from the sibling get_issue_hashes by framing the relationship as a hash comparison, so an agent can differentiate without opening schemas.

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 states the operating context (takes the issue's latest event) and points at get_issue_hashes for hash comparison, which is a useful routing signal. It stops short of an explicit when-to-use/when-not rule or the condition that selects one tool over the other, so it is clear context rather than full guidance.

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