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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false), and the description adds real behavioral context: merge-not-replace semantics, the intentionally immutable trigger_key, and the migration path for renaming. It stops short of noting auth/permission requirements or what the response returns, but it meaningfully exceeds the annotations.

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?

Roughly five tight sentences, front-loaded with the merge semantics that govern every other decision, then use cases, then the immutable-field caveat, then the prerequisite. No filler and no repetition of 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?

For a 16-property mutation tool with no output schema, the description supplies the critical missing frame: partial-update semantics, required trigger_id, sibling tools for lookup, and the non-editable field. It does not address validation failures or permission requirements, a minor residual 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 already 100%, so the baseline is 3, but the description adds meaning the schema cannot: trigger_key is deliberately not an accepted property, so an agent should not attempt it, and renaming requires a create+migrate+delete sequence instead. It also summarizes the editable surface (template, name, description, is_active, guardrail flags) before the schema enumerates it.

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+resource ('Update fields on an existing email trigger') and immediately qualifies it as PATCH-style partial update, which clearly separates it from meisa_create_trigger, meisa_delete_trigger, and meisa_activate_trigger. An agent can select it 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?

Explicitly enumerates the use cases (repoint template, change name/description, toggle is_active, update guardrail flags), the required prerequisite ('Requires the trigger_id (use meisa_list_triggers to find it)'), and the alternative workflow for renaming ('create a new trigger and have callers migrate before deleting the old one'). Alternatives and preconditions are all named.

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