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

Annotations only declare it is a non-read-only, non-destructive, closed-world write. The description adds real behavioral context beyond that: every call creates a new squad even with a duplicate name, and two specific failure conditions (no player card, no Squad Pro seat) with a reason and link returned.

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 tightly-packed sentences, front-loaded with the action and return value, then the confirmation guidance, then the duplicate-call and failure-mode warnings. No sentence is redundant.

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?

With no output schema, the description compensates by naming the return value (invite link) and the error shape (reason plus link). Combined with full parameter coverage, an agent has everything needed to call it correctly and interpret a failure.

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 the schema already documents all five parameters including aSide's 3-11 range and timezone format. The description only alludes to 'name and size', which adds negligible meaning over the schema, so the baseline 3 is appropriate.

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 ('Start a new Squadcard squad'), plus who becomes organiser and what is returned (the invite link). It is clearly distinguishable from siblings like join_squad, get_squad and list_squads.

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?

Explicitly states when to use it ('Confirm the name and size with the user first') and, more importantly, when NOT to repeat it, naming list_squads as the way to check existing squads before creating a duplicate.

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