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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds nothing behavioral beyond that, and 'Returns: {error}' reads like an unfilled template placeholder that conveys no real information about output or failure behavior.

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 with the core computation front-loaded, which is good. But 'Returns: {error}' is an unresolved placeholder that consumes space without earning it.

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?

An output schema and full annotations exist, so the description need not explain returns or safety. The parameter set is fully documented in the schema. Still, the description is thin for a math tool with a formula-dependent input convention (centered sums, not raw sums), and the list_bundles pointer is only marginally relevant.

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% and all five required parameters are individually documented, so the schema carries the burden. The description adds only the collective term 'summary statistics' and clarifies no individual parameter semantics beyond what the schema states — baseline 3 is appropriate.

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 (calculate) and resource (linear regression slope and intercept), plus the input modality ('from summary statistics'). It is clear what the tool computes, though it does not distinguish itself from near-siblings like calculate_slope or calculate_statistics.

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?

'From summary statistics' implies the input precondition (you must already have means and sums, not raw data), which is genuinely useful context. However, there is no explicit when-to-use/when-not guidance, and the pointer to 'list_bundles for related math calculators' is a navigation hint rather than a decision rule for choosing this tool over calculate_slope.

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