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

With readOnlyHint already declaring a safe read, the description adds real value: results are scoped to the authenticated user's own postcards, are sorted newest-first, and drafts are included by default (a non-obvious disclosure that prevents an agent from assuming drafts are hidden). It does not address pagination behavior or the shape of results, so not a 5.

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, zero filler; the default-inclusion-of-drafts detail is front-loaded where an agent will read it 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?

No output schema exists, so the description should carry the return shape — it conveys ordering and content scope but not what a postcard record contains. For a simple zero-required-parameter list tool with annotations covering safety, this is nearly complete.

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 75% and the status enum is self-documenting, so the schema does most of the work. The description reinforces the status filter and the draft value specifically, but says nothing about 'limit' (default 25, max 100) or how last_name/company_name partial matching interacts with each other.

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 ('List existing postcards'), plus scope ('for the authenticated user') and ordering ('newest first'). That is enough to distinguish it from the singular get-postcard-tool, though it never names a sibling explicitly.

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 gives one concrete usage cue — filter by status to find drafts needing to be sent — which implies the browse/filter use case. It does not say when to prefer get-postcard-tool for a single item, nor mention any prerequisites or exclusions.

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