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

Annotations already cover readOnly, idempotent, openWorld and non-destructive, so the bar is lower, and the description adds real value beyond them: text is fetched live from the public-domain CAP static mirror and is not stored, and the return includes per-opinion authorship. It stops short of noting any rate limits or pagination/truncation behavior beyond max_chars.

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 sentences with the core purpose front-loaded and no filler; the source-of-data and max_chars details are usefully appended. Tight and well-ordered, though the id-source note partially duplicates the schema.

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 carries return-shape burden and does so by describing the opinion set and authorship, plus the live-fetch/not-stored nature of the data. For a simple two-param read tool this is nearly complete, missing only explicit truncation behavior when max_chars is exceeded.

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 coverage is 100%, so the schema already documents both params (id source, max_chars default 50000 / max 500000). The description's 'Use max_chars to bound the response' and id-origin mention are consistent but add little beyond what the schema states, so the baseline 3 applies.

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 ('Fetch the full opinion text of a case') keyed to the CAP id, and clarifies it returns each opinion (majority, dissent, concurrence) with author. The 'full text' framing implicitly distinguishes it from caselaw_case_details/caselaw_search, but it never names a sibling explicitly.

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?

'On demand' and the id-source note (from caselaw_search / caselaw_citation_lookup) hint at the workflow, and 'Use max_chars to bound the response' gives a practical cue. However, there is no explicit when-to-use-vs-alternative guidance for choosing this over caselaw_case_details, so usage is only implied.

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