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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile needs no repeating. The description adds genuinely new behavioral context — the shape of the rendered result (statblock fields for actors, core fields plus system data for other types) — which matters because there is no output schema. It stops short of noting size limits or pagination, hence a 4 rather than 5.

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 tight sentences with no waste: purpose first, then the return shape, then sibling routing. Each clause earns its place and the most decision-relevant information is front-loaded.

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 two-parameter read tool with no output schema, the description covers what is returned, how the return differs by document type, and how to obtain the required IDs. Nothing an agent needs to invoke it correctly is missing.

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% and both parameters are documented there, so the schema carries the load. The description adds no format or syntax detail for packId/documentId beyond the schema; it only implies where IDs come from. 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 ('Get a compendium document') plus the scope of the returned value ('as a readable summary'), including what an actor document becomes (statblock with HP, AC, abilities, attacks). It is clearly distinguishable from compendium-document-get-raw and uuid-resolve, which it names.

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 routes the agent: use compendium-document-get-raw for raw JSON, uuid-resolve when holding a UUID, and compendium-browse to obtain document IDs. The conditions that select each sibling tool are stated rather than inferred.

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