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

Annotations already declare read-only, idempotent, closed-world, non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context: values are verified from the model file and must be quoted verbatim rather than estimated or filled from training recall. It says nothing about response size or structure, but with no output schema that is a secondary gap.

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?

Roughly three sentences, front-loaded with what the tool returns before the anti-fabrication constraint. The ALL-CAPS 'ANTI-FABRICATION' label is mildly noisy but earns its emphasis by flagging a hard quoting requirement.

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 single-parameter read-only lookup with a fully documented enum and no output schema, the definition covers purpose, trigger, and trust contract. The one remaining gap is that it never sketches the shape of the returned facts (fields, units, rough size), which matters somewhat given there is 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?

The single `chapter` parameter already has 100% schema coverage with a detailed enum description explaining the bs<N>-<ct|leds> format and the 5-vs-36 interrupt distinction. The description references 'the selected chapter' but adds no format, default, or track semantics beyond the schema, so baseline 3 applies.

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 resource ('structural facts of the selected chapter') and enumerates the contents: topology, rate limits, interrupt distributions, expected efficiency. That enumeration implicitly separates it from get_chapter_narrative and the run_* simulation tools, but no sibling is named explicitly, so the distinction is inferred rather than stated.

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?

'Use when the user asks about the line's configuration' gives a clear trigger condition. It does not say when NOT to use it, nor does it point to get_chapter_narrative or explain_concept for adjacent question types, so routing between the fact-lookup and narrative tools is left to the agent.

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