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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), so the bar is lower. The description adds value beyond annotations by disclosing the output payload shape (per-source last success, staleness in days, source URL) and the zero-cost behavior, which helps an agent anticipate what the call returns.

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?

Three sentences, every one earns its place: the opening states scope and cost, the second details the returned fields, and the third gives the usage context. The most important distinguishing fact ('Free', 'every data source') is front-loaded.

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 parameterless, read-only tool with no output schema, the description is nearly complete: it explains the return contents and when to use it. Minor gaps remain (e.g., how never-succeeded sources are represented, whether all sources are always listed), but none are critical for correct invocation.

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 has zero parameters, so there is nothing for the description to document; the baseline is 4. The description compensates by explaining what the response contains, which is the only semantic content an agent needs for a parameterless call.

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 names a specific resource — freshness of every data source — and specifies the exact per-source fields returned (last successful snapshot/event, staleness in days, public URL). It clearly differentiates itself from the sibling asset-specific tools (spot_*, gpu_*, etc.) by being a cross-cutting status/meta tool, and the title 'Data freshness' reinforces the purpose.

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 final sentence gives an explicit decision context: use this to check whether a fixing or quote is current before paying for it, and the opening 'Free' implies it is the no-cost way to do this check. It provides clear context but does not name alternative tools or state when not to use it, so it falls short of full routing guidance.

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