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

Annotations already declare readOnly, idempotent, non-destructive behavior. The description adds useful context beyond that: text is 'retrieved live from the public-domain CAP static mirror (not stored)' and includes each opinion type with its author, which helps the agent understand what will happen when invoked.

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?

The description is compact and well-structured: the core action is front-loaded, followed by data-source behavior, output composition, and a parameter-bound usage note. Every sentence earns its place.

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-only tool with rich annotations, this is largely complete: it identifies the input, source, output content, and response bounding. Minor ambiguity remains about the exact return format or behavior when max_chars is exceeded, but no output schema exists to fill that 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 both id and max_chars are already documented structurally. The description adds only that max_chars bounds the response and that the id is a CAP case id, which does not significantly extend the schema's own parameter documentation.

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?

The description states a specific action ('Fetch the full opinion text of a case') and the required identifier ('by its CAP id'), making the core purpose clear. It does not explicitly differentiate from siblings like caselaw_case_details or caselaw_search, though 'full opinion text' and 'CAP id' imply a distinct retrieval role.

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 implies when to use the tool ('on demand by its CAP id' and 'Use max_chars to bound the response'), but it does not explicitly state alternatives or when not to use it. The schema's id description points to caselaw_search/caselaw_citation_lookup as sources, but the description itself offers only implied usage context.

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