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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds non-annotation context that matters: this is a text-only content comparison and cannot assess pronunciation, fluency or prosody. It stops short of noting behavior for an invalid or non-Read-Aloud questionId.

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?

Three sentences, front-loaded with the usage condition, then the comparison behavior, then the boundary and alternative. No filler; every clause carries information an agent needs for selection or invocation.

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?

The tool is simple (two required, fully documented params, output schema present to explain return values), and the description covers the selection condition and the tool's key limitation. Nothing needed to call it correctly 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 description coverage is 100%, and the schema already explains that questionId comes from speak_practice or practice_question and that transcript is the student's spoken text. The description reinforces the transcript's provenance ('for example from voice mode') but adds no new constraints such as length limits or exact-match rules. Baseline 3 applies when the schema carries the parameter detail.

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 and resource ('Compares the words said against the passage') and enumerates the outputs (omitted, inserted, substituted words, word-accuracy percentage). It is clearly distinguishable from the recorder_* and speak_practice siblings, which handle audio-based scoring.

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?

Gives an explicit trigger ('Use when a student has read a Read Aloud passage aloud and you have the transcript ... but no audio') and an explicit exclusion with alternatives ('pronunciation, fluency and prosody need a recording: offer speak_practice or the answer link'). When-to-use, when-not-to-use, and the routing target are all present.

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