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

Goes well beyond the annotations (which only say non-readOnly, non-idempotent, non-destructive) by disclosing that the operation is free of credit cost, that the server auto-places unpositioned cards in the first free grid cell, and that the response contains the whole board plus the new card. The detailed sign-in/OAuth-vs-API-key requirement is exactly the kind of auth context an agent needs before invoking.

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?

Front-loads the action and behavior, then cost, then returns, then auth conditions — a sensible ordering with no filler. The auth sentence is long and URL-heavy, but it carries necessary setup information rather than padding.

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?

Covers the mutation's behavior, cost, placement defaults, and authentication prerequisites, and an output schema exists so return values need not be spelled out. Nothing critical is missing for an 8-parameter mutating tool, though a brief note on revision conflicts would have closed the last gap.

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 every parameter is already documented, including the nested position {x, y}. The description restates the position-omission behavior but adds no new meaning for parameters like revision, color, or width/height, so this lands at the baseline 3.

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 (add) and resource (text card) and clarifies the resource with concrete examples ('a note, an idea, a script line'), which cleanly separates it from add_frame, add_media_card, and add_generation_card. An agent can pick this tool 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?

Gives clear operating context: it places the card on a grid unless a position is supplied, and explicitly notes it costs no credits, which is decision-relevant when choosing between this and credit-consuming generation tools. It never names a specific alternative or states an explicit when-not-to-use condition, so it falls short of a 5.

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