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

Annotations only tell the agent this is not read-only and not destructive; the description supplies the far more important behavioral facts — the text is spoken aloud, statuses drive what the user hears, summaries must be speech-friendly, and secrets must never be included. That is context the structured fields cannot convey.

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?

Purpose and medium are front-loaded in the first sentence, then usage cadence, then formatting and safety constraints. Every clause carries operational instruction; none is filler.

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?

There is no output schema, and none is needed: the description explains exactly what happens to the input (it is read aloud) and how often to call. With five parameters at full schema coverage plus this behavioral framing, an agent has everything required to call it correctly.

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%, so the baseline is 3, and the enum values are already documented in the schema. The description still adds meaning beyond it by constraining summary content ('no markdown, URLs or code') and insisting on a stable bot_name across calls, which the schema only implies.

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 (report progress to the Heard app) and explains the concrete outcome: it is read aloud on the user's Mac. This is clearly distinguishable from the heard_inbox siblings, which concern inbox messages rather than progress reporting.

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 explicit when-to-use guidance ('Call it on every task'), maps each lifecycle moment to a status value, and even scopes frequency ('working at real milestones (not every step)') and the blocking condition for needs_input. Little is left to inference.

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