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

The annotations already establish a safe read (readOnlyHint=true, destructiveHint=false), so the description's job is to add behavior, which it does: a 60-day default window and an ingest-time bot exclusion that is only bypassed when include_bots is true. That is exactly the kind of non-obvious filtering rule an agent could not infer from the schema.

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?

Three tight sentences with no filler. The core purpose is front-loaded, followed by the default-value rule and then the filtering caveat. Slightly more could be trimmed, but nothing here 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?

Because an output schema exists, return shape does not need to be explained. The description covers the two behavioral facts an agent would otherwise miss (default window, bot exclusion) and is sufficient for a read-only tool. Its only gap is the unexplained distinct_id, which the agent must infer is the target user.

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 only 25%: project_id and time_range are documented in the schema, distinct_id has no description, and include_bots relies entirely on the description. The description usefully explains time_range's default and include_bots' effect, but leaves distinct_id's role ('user profile') implicit, so it only partly compensates for the coverage gap.

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 a specific verb and resource: 'returns per-day event counts for a user profile over a time window'. This is more precise than the title alone, though it does not distinguish it from close siblings such as get_activity_feed or get_profile_stats.

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?

The description strongly implies usage through the default time window and the bot-exclusion rule, but it never explicitly states when to choose this tool over get_activity_feed, get_profile_stats, or query_insights. There are no exclusion conditions; the reader must infer choice from the name alone.

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