Bind Rune

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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the description earns credit for adding the cost tier ('10 credits (Tier 1)') and the concrete return composition. It does not cover error behavior when more than four runes are supplied or how intent resolution fails.

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?

One dense sentence carries purpose and return shape, followed by a compact metadata block for group, endpoint, and cost. The output enumeration is a little packed into the same sentence, but nothing is wasted.

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 an output schema present and full schema coverage, the description covers purpose, both input modes, and cost. The remaining gap is guidance on mode selection and failure cases, which is minor for this complexity.

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 both parameters are already documented, including the enum slugs and 2–4 bounds. The description largely restates those bounds ('two to four runes', 'up to three' for intent) without adding format or fallback semantics. Baseline 3 applies when the schema does the heavy lifting.

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 — joining two to four runes onto one stave — plus the alternate intent-driven mode and the return payload (rune, poem stanza, SVG, combined stroke coordinates). An agent can distinguish binding from the draw/spread siblings. It stops short of an explicit contrast with astroway_runes_single or astroway_runes_three, which keeps it from a 5.

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 parenthetical '(or the runes whose meanings name an intent)' implies the two mutually exclusive input modes and thus how to choose between them. There is no explicit when-to-use/when-not-to-use guidance and no routing to sibling rune tools. Usage is inferable but not stated.

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