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

readOnlyHint already covers the safety profile, and the description adds real behavioral value beyond it: tiles the plan or data cannot answer return as 'unavailable' rather than 0, which prevents an agent from misreading a missing metric as zero. It also discloses that a comparison period is included in the response, which matters given there is no output schema. It stops short of explaining how the comparison period is derived.

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 short sentences, front-loaded with the core result and followed immediately by the most surprising behavior (unavailable, never 0). Nothing is padding.

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 read-only tool with no output schema, the description covers the essential contract: what comes back (per-tile figures plus prior-period comparison) and how failures are represented. The remaining gap is the 'id' parameter and whether the comparison period mirrors the requested span.

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 description coverage is 67%: periodStart and periodEnd are documented in the schema with format and meaning, but 'id' has no description at all. The description refers to 'a period' without clarifying inclusion semantics or that the comparison window is derived from the supplied period, so it adds little beyond the schema.

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 gives a specific verb-less but concrete outcome: every tile's figure for a period plus the prior period for comparison. That distinguishes it from get_dashboard (definition) and update_dashboard (mutation) well enough to choose it, though it never explicitly says it operates on the dashboard identified by 'id'.

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?

There is no explicit when-to-use or when-not-to-use guidance and no sibling is named, despite close siblings like get_dashboard, evaluate_report, and evaluate_report_batch. Usage is only inferable from the fact that figures for a period are returned.

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