Popularity sources

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely non-derivable behavior: it reveals that credentials are never returned (a security/privacy guarantee an agent needs when deciding what to report) and that each source carries a store scope and last-fetch timestamp.

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, zero filler, and the core answer (which sources are connected) is front-loaded before the two qualifiers. The 'REAL' emphasis cheaply signals that placeholder/unconfigured sources are excluded.

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 parameters, no output schema, and full annotation coverage, the description carries the remaining burden and does so: it enumerates the source kinds and the fields returned (store, last fetch). A slightly fuller account of the response shape (e.g. whether disconnected sources appear with a null timestamp) would close the last gap.

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?

The tool takes zero parameters, so the schema carries no semantic load the description must compensate for. The description spends its words on the return shape instead, which is the right allocation.

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?

Names the specific resource (connected popularity sources) and enumerates the concrete source types (Apple Ads, Google Ads Keyword Planner, imported files), plus what metadata is returned (store, last fetch time). It reads clearly as a status/introspection read, distinguishing it from the sibling mutators connect_popularity, disconnect_popularity and fetch_popularity, though it never names those alternatives explicitly.

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 framing ('which ... are connected') implies the use case: inspecting source state, likely before fetch_popularity or connect_popularity. But there is no explicit when-to-use statement, no exclusion, and no pointer to a sibling alternative, so the routing is left to inference.

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