session_send

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

With no annotations, the description carries the full burden; it discloses the busy-contention policy (reject default, queue, fork) and the return shape (new run_id and wait_cmd). It omits whether the call mutates state, cost/permission implications, and cross-bot auth requirements — meaningful gaps for a mutation-style tool with 18 params.

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 tight, front-loaded sentences with no filler; the busy-handling behavior and return values come first. It is efficient but arguably too terse for an 18-parameter tool.

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 an 18-param tool with no annotations and only 28% schema coverage, the description is thin — it covers busy handling and return values (aided by the output schema) but leaves most parameters, cost behavior, and mode semantics undocumented. An agent would need to guess at much of the surface.

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 28%, so most of the 18 parameters (mode, model, effort, notify, max_turns, timeout_min, allowed_tools, cross_bot, continue_interrupted, run_id) are undocumented in both schema and description. The description only illuminates if_busy/fork semantics, leaving the bulk of the parameter surface unexplained.

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: 'Follow up on an existing session (claude --resume)', which clearly contrasts with session_start's new-session role. The parenthetical anchor makes the operation unambiguous, though it stops short of naming the 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?

'Follow up on an existing session' implies this is for continuing a session already in flight, and the busy-handling sentence gives conditional guidance for reject/queue/fork. However it never explicitly says when to use this vs session_start or session_wait, and there are no prerequisites or exclusions.

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