Acquisition

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

Annotations already declare read-only, idempotent, closed-world, non-destructive behavior, so the bar is lower, yet the description still adds value: the 400-day range cap, the 'to is at most today' time-zone-scoped rule, and the explicit warning that all reported text is raw visitor-supplied input (a data-provenance/injection caveat). The attribution rule defining source vs (ad click) vs (direct) further clarifies output semantics.

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?

Content is front-loaded: the first sentence states what the report contains, then attribution logic, then prerequisites/limits, then the data-provenance note. It is somewhat dense in the attribution paragraph but every sentence carries non-redundant information.

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 does the work of describing the returned content (channels, sources, campaigns, conversions, ad clicks) and the key operational limits (400-day cap, today ceiling, time zone, list_projects dependency). It is close to complete, with only minor gaps around return shape/pagination.

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 already 100%, so the baseline is 3, but the description adds constraints the schema lacks: the range covers at most 400 days, dates are in the project time zone, and project_id/today must be sourced from list_projects. That meaningfully extends the three documented parameters.

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 names a specific verb-like resource (a per-day, per-channel acquisition report) and enumerates the channels it breaks out (paid, email, social, campaign, organic, referral, direct) plus the metrics it carries (visits, sources, campaigns, conversions, ad clicks). An agent can tell this is a traffic-attribution report, though it never explicitly contrasts itself with siblings like visits or overview.

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 a real prerequisite — 'The project id and the project's today come from list_projects' — and constraints on the date range, which is useful workflow context. However, it never says when to pick acquisition over the other reporting siblings (visits, overview, funnel), so selection guidance is only implied.

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