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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds non-obvious access-control semantics — the ownership/recipient visibility rule and the exact not_found outcome — which is genuine value beyond the annotations, though broader failure or paging behavior isn't described.

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 core action, and the access constraint follows. Every clause earns its place with no repetition of schema material.

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?

Output schema exists, so return values and the delivery rows need no prose explanation. Access rules are covered and tenant targeting is fully handled in the schema, leaving nothing an agent needs before calling it.

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 reminder_id and the tenant_slug workspace-selection rule are fully documented in the schema. The description only echoes 'by id' and adds no syntax or usage detail beyond what the schema states, so 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 (fetch) and resource (a single reminder) plus the accompanying delivery rows, which clearly separates it from kb_reminders_list. An agent can pick this over the list sibling without reading either 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 description scopes when this works ('only reminders you created or receive are reachable') and that misses return not_found, which is clear contextual guidance. It doesn't explicitly name kb_reminders_list as the browsing alternative, so it falls short of the 5 bar.

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