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

Annotations already indicate idempotent, non-read-only, non-destructive. The description adds practical behavioral details: the session starts empty ('starts with no tracks'), returns a shareable URL, and explains the idempotency_key retry semantics to avoid duplicates. These go beyond the annotation flags.

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 description is exactly three sentences, front-loaded with the primary action and outcome, followed by the empty-state behavior and idempotency note. Every sentence adds value with no redundant or filler content.

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 3-parameter creation tool with no output schema, the description covers the core action, return value (shareable URL), initial empty state, and how to handle retries. It also points to edit_session for subsequent modifications, making the tool's role in the larger workflow clear.

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?

All three parameters (name, tempo, idempotency_key) have detailed schema descriptions, so the tool description does not need to repeat them. The phrase 'normal defaults' loosely references defaults but adds no new parameter-specific information beyond the schema. Baseline 3 applies given 100% schema coverage.

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 states 'Create a new editable Keyboardia session with the normal defaults and return its shareable URL' with a specific verb, resource, and expected output. This clearly distinguishes create_session from siblings like edit_session, publish_session, and remix_session.

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 description explicitly directs users to 'use edit_session to add them' for tracks, establishing when to use this tool for initial creation versus edit_session. It also provides retry guidance for idempotency, reinforcing appropriate usage during uncertain attempts.

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