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

Annotations already establish read-only, idempotent, non-destructive and open-world behavior, so the bar is lower. The description adds real value beyond them by naming the upstream source (FJC directory) and enumerating the returned fields (name, title, appointing president and party, commission date, service status), which is behavioral context the annotations do not carry. It stops short of covering rate limits, pagination behavior, or handling of ambiguous court names.

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 paragraph that front-loads the core action, then the filter options, then return fields, ending with concrete example questions. Every sentence carries information, though the court-name examples are repeated between description and schema, which is mild redundancy.

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?

There is no output schema, but the description compensates by enumerating the returned fields, and the schema fully documents all three parameters including defaults and the total-count guarantee. An agent has everything needed to select and invoke this tool correctly without follow-up.

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 the baseline is 3. The description's restatement of the status filter ('active service only, active or senior status, or everyone since the court was created') largely duplicates the enum description in the schema, and it adds no new detail about the court string matching or the limit semantics.

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?

Specific verb ('List US federal judges') plus resource ('who sat on a given federal court'), with concrete scope examples (Supreme Court, Ninth Circuit, SDNY) and a named data source (FJC directory). It is clearly distinguishable from siblings fjc_judge_lookup (single judge) and fjc_judges_by_president (grouped by appointing president).

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?

Usage is well framed through the filter enumeration (active / serving / all) and two sample questions ('who are the active judges on the Fifth Circuit', 'how many judges has SDNY had'), which tell the agent exactly what class of question this tool answers. However, it never explicitly names the alternative tools (fjc_judge_lookup, fjc_judges_by_president) or states when not to use this one, so no exclusions are provided.

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