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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so safety is covered. The description adds real interpretive context the annotations cannot: totalErrorsInWindow is the full-window count while services is truncated to top-N, which prevents misreading the result as incomplete data. No auth or rate-limit notes, hence not a 5.

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?

Four tight sentences with the core action and the sibling ordering front-loaded. The middle sentence on window precedence partially duplicates schema text, which is the only wasted space in an otherwise dense definition.

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 7-parameter read-only aggregate with an output schema and full annotation coverage, the description supplies everything an agent needs: what is grouped, how the window resolves, how to read the two result fields, and where it sits in the error-triage flow.

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 100%, so the baseline is 3. The description restates the from/to/hours precedence that the schema itself already documents ("overrides hours", "default now when from is set"); the only marginal addition is the concrete now-${hours}h window expression. env, query, and context_id receive no added meaning in the description.

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 and resource — aggregate error counts grouped by service over a time window — and explicitly positions itself as the discovery step before dd_errors_recent, so it is distinguishable from its closest sibling without reading either 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?

Gives explicit sequencing ("Discovery step BEFORE dd_errors_recent") and parameter-selection preference ("Prefer from/to for historical windows; hours is used only when from is omitted"). It stops short of stating when this aggregate view is the wrong choice versus other error siblings, but the primary routing guidance is present.

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