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

Annotations declare the safe/non-destructive profile, but the description adds real behavior beyond them: the caption is truncated to the tightest limit among the target platforms, a draft id is returned, and the draft surfaces under /drafts for review. It omits that the call is non-idempotent (repeated calls create separate drafts) and says nothing about auth or limits.

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 sentences, zero filler, with the action and the most non-obvious behavior (tightest caption limit) front-loaded and the return/review consequence trailing. Every clause earns its place.

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 create tool with no output schema, the description covers the action, the shaping rule, and the return value (a draft id) and where the artifact lands. It stops short of stating any prerequisite account/profile context, which is a minor gap against a 5-param tool.

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 100%, so the schema already documents all five parameters and the enum values. The description adds only the conceptual framing that platforms drive the caption length ceiling, which the platform param description already states, so baseline 3 is appropriate.

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 ('compose a caption ... save it as a draft in sprkly') plus the scope of the computation ('shaped to the tightest caption limit among the target platforms'). It is distinguishable from sprkly_schedule_post by the draft-not-scheduled outcome, but it never names that sibling or any alternative 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?

Usage is only implied: 'save it as a draft ... for the user to review' suggests this is the pre-publication step before scheduling, but there is no explicit when-to-use statement, no condition that selects this over sprkly_schedule_post, and no prerequisites (e.g. whether a connected account or profile is required).

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