explain_license

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

Annotations already establish that this is a safe, idempotent read, and the description still adds real behavior: an embedded hand-written table of ~50 licenses, a hard coverage ceiling, and an explicit refusal to guess on unknown ids. The 'Does not read any files' note and the deprecated-id normalization rule ('GPL-2.0' read as 'GPL-2.0-only') are details an agent could not recover from annotations or schema.

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?

The first sentence states what the tool produces, the second enumerates accepted input forms, and the third states the coverage limit and the no-file-access guarantee. No sentence is redundant, and the most decision-relevant content leads.

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 lookup tool with an output schema, nothing essential is missing: input formats, coverage bounds, and the out-of-scope behavior are all stated. Return-value details are correctly left to the 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?

Schema description coverage is 0%, so the description carries the full burden for the single spdx_id parameter, and it does: it lists accepted forms (SPDX id, common spelling like 'Apache 2', deprecated id, and compound expressions with OR/WITH) with concrete examples. This is meaning well beyond the bare untyped string the schema exposes.

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 description names a specific verb and resource ('Explain a license') and enumerates the shape of the answer ('what you can do, what you must do, and the limits'). It also explicitly excludes a neighboring capability with 'Does not read any files', which separates it from find_license_files and license_inventory without requiring either schema to be opened.

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?

Usage is framed clearly: reach for it when you have a license identifier or expression and want a plain-language reading, and it states the failure condition ('for others it says so rather than guessing'). It does not, however, say when to prefer compatibility or check_policy over this tool, so the agent must infer the boundary itself.

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