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 genuinely new operational context: it renders a recorder card and is 'desktop web only today,' a platform constraint an agent could not derive from structured fields. It stops short of saying what happens on unsupported platforms or how the recorder_start/recorder_result siblings relate, which keeps it off a 5.

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 short sentences, front-loaded with the usage trigger before the capability statement and the exclusion. Every clause carries information. The semicolon fragment 'Shows a recorder card; desktop web only today' is terse but dense with useful constraints, so only minor polish is missing.

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?

An output schema exists, so return values need no explanation, and the description still tells the agent what the student gets back (pronunciation and fluency scores). For a two-optional-parameter read-only tool this is close to complete. The remaining gap is the platform fallback and the handoff to the recorder_* siblings, which the description never mentions.

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 both parameters carry enum values and inline descriptions, so the schema already does the heavy lifting. The description maps its prose to the taskType values ('Read Aloud', 'Describe Image') and confirms the PTE focus that matches the exam default, but adds no syntax or format detail beyond that. 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?

The description names a specific verb and resource: it lets a student practise a PTE Read Aloud or Describe Image speaking task and receive pronunciation and fluency scores. It also distinguishes itself from text-scoring siblings with the closing 'Do not use for scoring text.' An agent can separate it from score_writing and check_read_aloud without opening any 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?

The trigger condition is explicit and unusually generous: 'Use whenever a student asks for a PTE Read Aloud or Describe Image to practise, even without mentioning recording or scores.' The exclusion is equally explicit: 'Do not use for scoring text.' Both the when and the when-not are stated outright, leaving nothing to inference.

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