Explain a code

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

The description restates readOnlyHint and openWorldHint=false ('read-only lookup, no network'), which is redundant against annotations, but it adds genuinely new context by declaring the return structure {summary, try[], evidence_needed[]} in the absence of an output schema. With annotations already covering safety, the return-shape disclosure is the main value-add and it's a useful one.

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?

Telegraphic but front-loaded: purpose first, then when-to-use, then parameters, then behavior, then return shape. No sentence is filler, and the fragment style makes scanning fast.

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 one-parameter read-only lookup, the description covers trigger, siblings, input, safety profile, and output shape. There is no output schema, yet the return keys are enumerated, so nothing an agent needs to invoke and interpret the call is missing.

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 coverage is 100% and the single parameter carries a description, pattern, and example ('gpu.unavailable'). The description only notes 'code (required)', which repeats structured data without adding format or lookup semantics beyond what the schema already provides — baseline 3.

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 opening sentence states exactly what the tool produces: the meaning of a code, remediation steps, and settling evidence. It also distinguishes itself from stack_health (which surfaces the code) and stack_snapshot (data), so an agent can pick correctly without opening a 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?

Explicit sequencing guidance: 'after stack_health names a code' tells the agent when this tool is appropriate, and 'stack_snapshot for data' excludes the sibling that would otherwise look plausible. Both when-to-use and the alternative are named.

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