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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=true and openWorldHint=true, so the safety profile is covered structurally. The description adds real value beyond that by disclosing the partial-update semantics ('Only the fields you pass change'), which tells the agent that omitted fields are preserved rather than reset. It does not, however, explain what the destructive behavior actually entails or note any auth/rate-limit constraints.

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 short sentences, front-loaded with the WRITE marker and the field list, ending with the endpoint. No filler, no redundancy, and the most decision-relevant information comes first.

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 5-parameter mutation tool with no output schema, the description covers the operation type, the mutable fields and the partial-update rule, while annotations carry the write/destructive/idempotent profile. It stops short of explaining the return value and the meaning/units of 'frequency', but nothing essential for selecting or invoking the tool is absent.

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 only 20% (list_id is the sole documented parameter), so the description bears much of the burden. It partly compensates by naming the four optional fields that can be modified, mapping them to list_name, display_name, frequency and description. It adds no constraint detail (30/50/20 character limits, frequency range 1-999, or what 'frequency' measures), so the semantic picture remains incomplete.

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?

Opens with an explicit WRITE marker plus a precise verb+resource ('change a distribution list's') and enumerates exactly which fields are mutable (name, display name, frequency, description), which cleanly separates it from the read-only siblings like trumpia_get_list and trumpia_list_lists. The endpoint reference (POST /list/{list_id}) confirms the operation type. An agent can identify this tool 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?

'Only the fields you pass change' communicates partial-update behavior, which is meaningful invocation guidance. However, there is no explicit statement of when to choose this over trumpia_create_list or trumpia_get_list, nor any mention of prerequisites or auth. Usage context is implied rather than stated.

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