add_sticker_pack

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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=true, openWorldHint=true), but the description adds concrete meaning: the exact return shape {status: 'installed', pack_id}, that pack_id is parsed from the uri, and that re-installation is a no-op. It stops short of mentioning any auth or rate-limit considerations, but the added behavioral context is real.

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?

Front-loaded with the core action, then the input constraint, then the return value and routing. Every sentence carries information, though the inline uri format with angle-bracket placeholders makes the middle clause slightly dense.

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?

With no output schema, the description compensates by documenting the return payload and the parsed pack_id, and it names the downstream tools (send_sticker, send_group_sticker, get_sticker) plus the inspection tool (list_sticker_packs). Nothing needed to invoke this correctly is missing.

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% with a single uri parameter, but the description goes beyond the schema by spelling out the required fragment structure (pack_id=<hex>&pack_key=<hex>) and stressing that both pack_id and pack_key must be present — a validation detail the schema's terse description does not convey.

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 ('Install') plus resource ('an existing sticker pack on this Signal account') and the required input format (signal.art link). It also explicitly distinguishes itself from upload_sticker_pack, which publishes new packs, so an agent can disambiguate 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?

Gives the when (install an existing pack via signal.art uri), the when-not/alternative (use upload_sticker_pack to publish your own images), and the repeat-call behavior (installing the same pack again has no further effect). It also routes to list_sticker_packs for inspecting pack contents.

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