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 and caching profile is covered. The description adds that results are causally scoped ('only the causal explanation'), which is useful, but says nothing about permission needs, result format, or what happens if no cause is found.

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?

A single tight sentence, front-loaded with the action and scoped by the parenthetical. No filler, though the sentence is short enough that structure is a minor factor.

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 simple one-parameter read tool with annotations covering safety, the description is serviceable. It is incomplete on parameter meaning (what 'id' refers to) and on behavior when no causal explanation exists, which matters given no output schema.

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?

One required parameter with 0% schema description coverage: the schema only gives 'id' as a string with no meaning. The description refers to 'one pattern' but never explains that the id identifies a pattern or whether it's a pattern id vs. other ids. With low coverage, the description should have compensated and does not.

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 action ('Return only the causal explanation') and resource ('one pattern'), and the parenthetical scopes what 'why' means (model/tool/template default). It distinguishes itself from get_pattern by emphasizing causation, but it doesn't explicitly name the sibling to use for non-causal pattern data.

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 word 'only' implies this is a focused query rather than general pattern retrieval, hinting get_pattern is the alternative. But there's no explicit when-to-use/when-not-to-use statement or named alternative, so guidance is only implied.

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