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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false and openWorldHint=true, so the write semantics are covered structurally; the 'WRITE:' prefix and POST endpoint merely restate that. It does add one piece of behavioural value the annotations lack: that the response carries an id to be consumed by sessions.

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?

Two short sentences, front-loaded with the operation type and the resource, then the follow-up usage tip, then the endpoint. No filler, and the most decision-relevant information comes first.

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 simple 3-parameter create tool with full schema coverage and no output schema, this is nearly complete: it says what is created, that an id is returned, and where that id goes. Minor gaps are the absence of failure conditions or whether duplicate names are allowed.

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%, so name, color and order are all fully documented with constraints (hex pattern, max length, 0-10000 ordering, default position). The description adds nothing beyond 'with a colour', so baseline 3 applies and the schema does the work.

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 ('add a label (track) for sessions') and even disambiguates the domain term by equating label with 'track'. Combined with the endpoint line, an agent knows exactly what this creates and that no sibling tool does the same job.

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 gives downstream guidance ('Use the returned id in label_ids of a session'), which implies the workflow ordering, but it never states when to create a new label versus reusing an existing one, nor any prerequisite (e.g., existing event/workspace context). Usage is implied rather than spelled out.

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