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

The description discloses critical behaviors beyond annotations: it WRITES to the account, keyless calls return auth_required, the response contains a saved site id, passing market snapshots a DCPI baseline, and the returned id can be fed to set_site_alert for monitoring. These are non-obvious side effects an agent must know, and they align with readOnlyHint=false.

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?

The description is long but every major block earns its place: auth warning, purpose, parameter summary, snapshot behavior, follow-up workflow, example, and exclusions. There is minor redundancy between 'track it across sessions' and 'persistent shortlist an agent can revisit', but overall it is well organized and front-loaded with the most critical warning.

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 mutating tool with auth requirements, persistent state, and side effects, the description is complete: it covers prerequisites, exact inputs, return value, downstream integration with set_site_alert, and exclusions. The output schema covers the return format, so the description's job is done.

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 coverage is 100% and each parameter is documented, but the description adds significant meaning: it flags lat+lon as the essential inputs, explains that passing market triggers the DCPI baseline snapshot, and the example maps concrete values to parameters. This goes beyond the bare schema definitions.

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 opens with a clear verb+resource: 'Save a candidate data-center site to your DC Hub account to track it across sessions.' It also distinguishes itself from siblings by explicitly naming list_saved_sites, export_dataset, and score_facility as tools not to use for reading back, downloading, or scoring.

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?

Usage is explicit and actionable: it instructs agents to call claim_free_key FIRST if keyless, provides a concrete example invocation, and states when NOT to use the tool with named alternatives (list_saved_sites, export_dataset, score_facility). The 'Answers...' line gives natural-language trigger phrases.

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