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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, and the description still adds genuine behavioral facts: a hard 31-day window cap, default-to-recent-history behavior, and a required project Read permission. What it omits is ordering/pagination behavior and what happens when the root has no reachable nodes.

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?

One long semicolon-chained sentence whose lead clause is the least comprehensible part of the text, so it is not front-loaded. Information density is high and there is little filler, but the structure actively impedes parsing the most important statement.

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 and four parameters, the description carries the return-value burden and largely meets it, naming the sections (revision, built-from, produced, elsewhere) plus ingestions, recalls and replacement edges. Auth requirements and the window default are also covered; only ordering and edge-case behavior are missing.

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 would be 3; the description earns above that by supplying the 31-day maximum for from/to and the default window semantics, which the schema does not state. It adds no extra meaning for project beyond the schema, but the window constraint is real parameter-level information.

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 does enumerate what comes back (reachable nodes with timestamps, ingestions, recalls, replacement edges), so the resource is identifiable as 'the history around a root node'. However the opening framing 'The work around a root on a clock' is cryptic rather than a clean verb+resource statement, and it never distinguishes this from adjacent tools like get_lineage, get_trace_node or find_trace_roots that also operate on trace roots.

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 gives a usable constraint ('window is at most 31 days, the root's recent history by default') and a prerequisite ('needs project Read'), plus the anchoring cue 'Mirrors Trace's Timeline tab'. But it gives no explicit when-to-use versus get_lineage or get_trace_node, which is the real selection decision an agent faces among these siblings.

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