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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds value beyond that by disclosing which related resources are expanded and warning that picklist custom-field values are option ids requiring a lookup — a real behavioral caveat an agent would otherwise hit at runtime.

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?

Two tight clauses plus the endpoint reference; the core action and scope come first and every element carries information. Nothing is padding, even the picklist parenthetical.

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 the burden of telling the agent what comes back, and it does name the major fields and the custom-field value encoding. It does not describe the full response envelope or how attorneys/practice area are nested, leaving a small gap for a read tool with an openWorld annotation.

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% and both parameters are documented, so the baseline is 3. The description still adds meaning by enumerating what the default response shape contains, which effectively explains the consequence of omitting the `fields` override, and by qualifying the domain of matter_id as a Clio numeric id.

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 a single matter by id") and enumerates the returned sub-resources (client, practice area, stage, attorneys, custom field values), which cleanly separates it from the sibling clio_list_matters. An agent can pick it out without opening the schema.

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 "single matter by id" framing makes the list-vs-get split clear, and it explicitly routes the agent to clio_list_custom_fields to interpret picklist values. It stops short of an explicit "for many matters use clio_list_matters" exclusion, so it is clear context rather than full when/when-not guidance.

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