impression_share

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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description's only added behavioral detail is "typed UTC request", which usefully signals that the YYYY-MM-DD start/end values are interpreted in UTC — a fact not present in the schema. It says nothing about latency, rate limits, or how granularity/reportType affect output shape.

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?

A single front-loaded sentence with no wasted clauses. It is admirably tight, though the phrase "through a typed UTC request" is the only content beyond restating the name.

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?

For a 9-parameter tool with 7 required fields and enum-like values (FIRST_SLOT/ALL_SLOTS, DAILY/WEEKLY_SUN_SAT) that are only tersely described in the schema, the description should explain what those options mean and how impression share is scoped. The output schema covers return values, but the request semantics are left almost entirely to the schema.

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 description coverage is 100%, so every one of the 9 parameters is already documented in the schema, which sets the baseline at 3. The description adds only the UTC framing for the date range and no meaning beyond that for reportType, granularity, or pagination.

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 states a specific verb and resource ("Read app impression-share insights"), so the agent knows this returns impression-share metrics rather than generic performance data. It does not distinguish the tool from reporting siblings such as ad_report, campaign_report or keyword_report, so the agent must infer the boundary from the name 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?

There is no statement of when to use this tool instead of the many sibling report tools, and no prerequisites are mentioned (e.g. needing a local profile or a specific ad account). The agent gets the purpose but no routing guidance.

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