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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the response is cache-backed and may legitimately be empty while the cache populates, which is exactly the kind of behavior an agent cannot infer from annotations.

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 compact sentences plus the REST endpoint, all front-loaded with the payload contents first and the caching caveat second. Nothing is redundant, though the endpoint path is marginally decorative for an agent that only needs the call semantics.

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 must sketch the return value, and it does: grand total plus breakdowns by project, language, editor, and more. Combined with the caching caveat, an agent has enough to invoke and interpret the call, though the exact nesting of the breakdown lists remains unspecified.

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?

Zero parameters, so the schema imposes nothing to document and the baseline is 4. The description correctly spends no words on parameters and instead describes the response shape.

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 gives a specific verb and resource — today's coding activity with grand total and breakdowns by project, language, and editor — which is clearly narrower than siblings like get_summaries or get_all_time_since_today. It stops short of explicitly naming the sibling alternative for non-today ranges, so an agent must infer the contrast from the date scope alone.

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 supplies one meaningful usage caveat: this returns cached data only, and an empty summary means the cache is still filling. That tells the agent how to interpret an unexpected empty result, but there is no guidance on when to prefer this over get_summaries or get_stats for overlapping date ranges.

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