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

The annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds value beyond that by disclosing the shape of the result — status counts, median latency, and the count of registry entries that cannot be tested — which tells the agent this is an aggregate/metrics read, not a listing of individual records. It does not cover timezone handling for the day boundary, which would have pushed it higher.

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, no filler, with the resource and scope front-loaded ahead of the default-behavior note. The clause "of working agents and tools" is slightly ambiguous — it is unclear whether the census covers both registries jointly or separately — but overall the text is tight and well ordered.

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 carries the burden of explaining return values, and it does so at a high level: status counts, median latency, and untestable-entry count. For a one-parameter, read-only metrics tool this is nearly sufficient; the remaining gaps (result format, whether the metric is scoped to a single day or cumulative) are minor.

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?

There is a single optional parameter with 100% schema coverage, where the schema documents the YYYY-MM-DD format. The description contributes meaning the schema does not: that the day is optional and defaults to the latest available census, which is the key behavior an agent needs to decide whether to pass the argument at all.

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 a specific resource ("the dated census of working agents and tools"), then enumerates the metrics it returns: counts by status, median latency, and untestable entries. It does not name a sibling to distinguish itself from, but the term "census" and the enumerated contents are distinctive enough that an agent can identify the operation without opening the schema.

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?

"day defaults to the latest" tells the agent the argument is optional and what happens if omitted, which is a real usage hint. However, there is no explicit statement of when to reach for this versus a sibling like agentrecord_lookup or agentrecord_search, and no exclusions or prerequisites. Usage is implied by the purpose rather than spelled out.

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