PrismPoster Creator Tools

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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real behavioral content: it returns centre-crop and letterbox/pillarbox plans with px trimmed or added per edge, and it errors on non-integer or out-of-range sizes and on only one of targetRatioW/targetRatioH. It stops short of stating rounding/precision behavior for the crop offsets, which keeps it from 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?

Front-loaded with the primary computation, then the alternative route, then error cases — a sensible ordering with no filler. The opening sentence is long and packs three distinct outputs into one clause, which slightly hurts scanability.

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?

An output schema exists, so return values needn't be spelled out, yet the description still characterizes what the plans contain (px per edge). Combined with sibling routing and explicit error conditions, nothing an agent needs to invoke it 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%, so the baseline is 3, but the description adds meaning beyond the schema: it explains the pairing constraint (targetRatioW/targetRatioH must both be supplied) as an error condition and illustrates ratio terms with 2.39:1 and 4:5. The width/height bounds themselves are left to the schema.

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 specific verbs and resources: reducing a pixel size to a simplest aspect ratio plus nearest even H.264-legal size, and solving the missing dimension for a target ratio with crop/letterbox plans. It even gives a concrete example (1920x1080 is 16:9), so an agent can tell exactly what it produces without opening the 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?

Explicitly names the boundary case ('arbitrary sizes and ratios (cinema 2.39:1, a client's 4:5)') versus the sibling route ('when the target is a named platform placement, use get_social_media_placement with sourceWidth/sourceHeight'), so the routing decision is fully determined.

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

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

Beyond the readOnly/idempotent/non-destructive annotations, the description discloses the verdict vocabulary ('inside', 'intrudes', 'unknown'), the meaning of 'unknown' for TikTok, that a reason is returned instead of a guess, and which inputs produce errors. This is rich behavioral context that annotations alone would not supply.

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?

Three tight sentences with no waste: purpose first, then the sibling alternative, then return/error behavior. Every clause earns its place and the most decision-relevant information is front-loaded.

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 an output schema present, the description need not explain return values, yet it still names the verdicts and the 'unknown' case. It also covers the error paths and the sibling relationship, leaving nothing important for an agent to guess.

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 per-parameter meanings are already documented as left/top edges and width/height in px. The description adds the global framing ('in px on the placement's own frame, origin top-left'), but that is largely a restatement of the schema's coordinate descriptions, so the 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 ('Check whether a rectangle ... stays inside the placement's safe area') plus the exact coordinate frame and origin. It is clearly distinguishable from the sibling get_social_media_placement, which is named as returning raw insets instead of a verdict.

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?

Explicitly says 'Use this to validate a layout before export' and routes the agent to get_social_media_placement when raw insets are wanted. The when-to-use and the alternative are both stated, so no inference is needed.

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

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

Annotations only cover the safety profile (readOnly, idempotent, non-destructive, closed-world), while the description adds substantive behavior: malformed blocks are skipped with a warning rather than failing the whole file, and hard failure conditions (no parseable cue, >2 MB input, shift beyond one hour) are spelled out. Return content — detected source format, cue count, warnings with line numbers, timing issues — is also disclosed.

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?

The core operation and the 'contents not path' rule are front-loaded, and every remaining sentence carries a real constraint. It is a dense single block, though, and the enumerated return fields partly duplicate what the existing output schema already provides, which is mildly redundant.

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 annotations covering safety, full schema descriptions, and an output schema, the description still supplies the pieces structured data cannot: input size cap, failure modes, graceful degradation on malformed blocks, and unsupported formats with a pointer elsewhere. Nothing an agent needs to invoke it 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% and already documents all three parameters well, so the baseline is 3. The description earns an extra point by adding constraints absent from the schema: the 2 MB input ceiling and the one-hour shift error condition, which give the caller limits the structured fields do not express.

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?

Names a specific verb and resource ('Convert subtitle text between SubRip (srt) and WebVTT (vtt)') plus the optional shift behavior, so the tool's scope is unmistakable. The siblings (aspect ratio, safe area, tempo, bitrate, social placements) are unrelated, so no disambiguation is needed and none is missing.

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?

Explicitly tells the caller to 'Pass the file contents, not a path', and defines an exclusion with a named alternative: 'ASS/SSA input is not supported here; the @prismposter/creator-tools package converts it.' This is exactly the when/when-not/alternative structure the dimension rewards.

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

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

Annotations already establish readOnly/idempotent/non-destructive, and the description adds real value on top: the failure surface (no input, unusable taps, bpm outside 30-300, unlisted time signature) and the signal that this is pure arithmetic on supplied numbers rather than audio analysis. It does not cover tap-to-bpm fallback precedence, which the schema handles.

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 dense sentences, front-loaded with the tool's identity and followed by inputs, outputs, and exception cases in call order. The middle sentence is long and carries several clauses, but no sentence is filler.

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 need not be re-specified, and the description still names them at a high level while covering both input modes, the output shape, and every documented error condition. An agent can call this correctly without further inference.

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 the baseline is 3, and the description earns a step up by framing the parameters as mutually alternative modes ('Either way') and restating the accepted bpm window and time-signature constraint at the point where an agent decides how to call it.

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?

Opens with a specific framing ('Tempo arithmetic for editing to music') and then enumerates the concrete outputs: BPM with stability/confidence, beat length, delay table, and bar duration. It also explicitly rules out the misinterpretation ('does not analyse audio'), which no sibling tool covers.

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?

Clearly states the two invocation modes ('pass tap timestamps... or pass a known bpm'), giving the agent an explicit choice criterion. It stops short of naming alternatives, but the sibling tools are unrelated utilities, so there is little to route between.

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

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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false, and the description still adds real value: the default audioKbps of 192, the guaranteed Discord 20 MB answer on every call, the error behavior when neither param is set, and the decimal vs binary unit convention. Only the exact return shape is left unexplained, and an output schema exists anyway.

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?

Purpose and required durationSec come first, followed by the two modes, then units and caveat — a sensible front-loaded order with no filler. Some sentences are heavily packed (units, Discord limit, and scope crammed into consecutive clauses), which slightly hurts scanability.

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 4-parameter, single-call calculator with an output schema, this covers everything an agent needs: what is computed, how to choose the mode, defaults, unit conventions, error condition, and what it does not do. Nothing material 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%, so baseline is 3, but the description adds semantics the schema lacks: kbps is decimal (1000 bit/s) and MB is 1,000,000 bytes, plus the mode-selection meaning of videoKbps vs targetCapMb. The audioKbps default of 192 is repeated rather than new.

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 combination: arithmetic to compute video file size and bitrate for a clip of durationSec. It also explicitly bounds scope with "it does not inspect or encode files," which distinguishes it cleanly from every sibling (aspect ratio, safe area, subtitles, tempo, placement).

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 two mutually exclusive invocation modes (pass videoKbps -> file size; pass targetCapMb -> max bitrate) and names the real-world situations: "plan an export or hit an upload cap." It also states the negative case (no file inspection/encoding) and the error condition when neither mode parameter is supplied.

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

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

Annotations already cover read-only/idempotent safety, but the description adds real behavioral detail: paired-parameter behavior that unlocks crop/letterbox planning, the TikTok null-inset case with its reason, and both error conditions (unknown id whose message lists valid ids, and a single source dimension). That is context the annotations cannot supply.

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 lookup and its return payload, then the optional dimension pair, then the sibling routing, then edge cases. Every sentence carries distinct information — no restatement of the title or schema types.

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 an output schema present, the description needn't detail return shapes, and it still names the returned fields. It covers the optional-input path, the known-degenerate platform (TikTok), and both failure modes — nothing an agent needs to call 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%, so baseline is 3; the description goes further by explaining what the optional pair actually buys you (centre-crop and letterbox plan fitted to your footage), which is outcome semantics rather than a restatement of types. Minor credit withheld because the id enum's camelCase/kebab-case duality is only handled in the schema.

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 (look up one placement by id) and enumerates exactly what comes back: frame size, aspect ratio, safe-area insets, usable box, source page. It is immediately distinguishable from list_social_media_placements and check_safe_area, which are named.

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?

Explicit routing: 'Use this when you know the target placement', then names three alternatives with the condition that selects each (browse/compare, test element clearance, compute a non-platform ratio). The when-to-use decision is fully resolved inside the description.

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

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

Annotations already cover read-only, idempotent, closed-world, so the description's additive value is "a fixed dataset returned whole, with no paging" — a genuinely useful operational fact that prevents an agent from hunting for pagination params. The field enumeration is somewhat redundant with the output schema, which keeps this short of 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?

Front-loaded with verb + resource, then routing guidance, then a behavioral caveat — a logical order with no filler sentences. The middle clause packing ~7 returned fields is dense but still readable.

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 single-optional-param, read-only list tool with an output schema and full annotation coverage, nothing an agent needs is missing: scope, filter behavior, no-paging semantics, and the alternative tool are all stated.

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% and the single enum param already says "Omit for all platforms." The description only echoes this with "(or one platform's)," adding no format, default, or edge-case detail beyond the schema.

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 every supported social media placement") and immediately names the returned data (frame size, aspect ratio, safe-area insets, usable box, source URL, CSV/JSON/DOI links). It is clearly distinguished from get_social_media_placement in the same breath, so an agent can pick between them without opening 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?

Explicit routing: "Use this to browse, compare platforms, or find a placement id; use get_social_media_placement when you already know the id and also need a crop/letterbox plan." Both the when-to-use and the named alternative with its selection condition are present.

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