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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower. The description still adds genuine behavior: the snapshot contents (share of AI answers, citations, mentions, competitor leaderboard, up to 12 earlier snapshots) and the null-when-never-measured edge case.

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 sentences, front-loaded with the action and resource, then the returned contents, closing with the null case. No filler; every clause carries 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?

An output schema exists so return values need not be spelled out, yet the description summarizes them anyway. With annotations covering safety and the schema covering the parameter, the definition is complete; only the sibling relationship is unaddressed.

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% for the single domain_id parameter, including its origin ('from list_domains'). The description adds no meaning beyond the schema, so the baseline 3 applies.

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?

States a specific verb ('Read') and resource ('a domain's latest AI Share of Voice snapshot') and enumerates what the snapshot contains. It is unclear only relative to the sibling refresh_share_of_voice, which is never named or contrasted.

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?

Implies it is the read path for a snapshot but gives no explicit when-to-use guidance, prerequisites, or routing against refresh_share_of_voice or list_domains. The agent must infer that this is the fetch-vs-refresh counterpart.

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