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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered structurally; the description adds the non-obvious behavioral rule that this should be called once per conversation rather than repeatedly. It says nothing about authentication requirements, rate limits, or whether the data is cached or live, which is the remaining gap for an open-world read.

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: the first front-loads verb and resource before the field list, the second carries the routing guidance. The long enumeration of returned fields is partly redundant given a rich output schema exists, which costs it a point, but there is no filler or hedging.

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 zero-parameter, read-only introspection tool with a full output schema, the description supplies everything an agent needs: what it returns, when to call it, and which siblings handle the follow-up questions. No operational detail required to invoke it correctly is missing.

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 there is no parameter semantics to explain and the baseline of 4 applies. The description correctly avoids inventing options and instead spends its words on scope and timing.

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?

Opens with a specific verb and resource ('Return this user's freddy account profile') and then enumerates exactly what comes back: identity fields, plan tier and billing status, entitlements, accepted policy versions, and per-source status. It is immediately distinguishable from siblings like connection_status (which covers a single source) and list_metrics.

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?

Gives an explicit timing instruction ('Call it once at the start of a conversation') plus the reason ('to learn who the user is and what data exists'), then names the two alternatives (list_metrics, query_metrics) with the condition that selects them. Nothing about when to reach for this tool 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.